Current Affairs 7th Class

*     Simple Interest                   In the case of simple interest, we calculate interest paid by borrower over certain period of time without changing its principle.                         Calculate the simple interest on a sum of $1200 at the rate of 5 % per annum or two years.                 Solution:                 The following steps are to be followed                 Step 1: The interest for first year when                 P =$ 1200, R = 5 % and T = 1 year                 S.I. \[=\frac{P\times R\times T}{100}=\frac{1200\times 5\times 1}{100}=\$60\]                 Therefore, interest for the first year is $ 60.                                 Step 2: Interest for the second year                 P = $ 1200, R = 5 % and T = 1 year                 S.I. \[=\frac{P\times R\times T}{100}=\frac{1200\times 5\times 1}{100}=\$60\]                 Therefore, interest for the second year is $60.                 Total interest paid by borrower after 2 years =$ 60 + $ 60 = $ 120.  

*     Compound Interest                   In this case we observe that the interest paid by borrower is same for every year.                 There are different methods to calculate the interest in case of bank transaction loan etc. In these methods, interest is calculated either quarterly, half yearly or yearly, what so ever may be the case. i.e. The agreement between the lender and borrower on the principle. The amount after that first fixed interval of time will be principle for second interval of time, the amount after second interval of time will be the principle for the third interval and so on. The interest paid by borrower under the above conditions is called compound interest.   *      Abbreviation used in Interest
  •  Principle as P              
  •  Time as T
  •   Rate as R or r
  •   Simple interest as S.I.
  •   Compound interest as C.I
  •   Amount as A  
                    Find the compound interest on a sum of $ 1500 for two years at the rate opf 5% per annum compounded annually. Solution: The following steps are followed Step 1: Principle for the first year = $ 1500, Time (T) =1 year R = 5 % p.a.                 \[S.I.=\frac{P\times R\times T}{100}=\frac{1500\times 5\times 1}{100}\$75\]                 Amount after 1st year \[=\$1500+\$75=\$1575\]                                 Step 2: Principle for second year = $ 1575, Time = 1 year, R = 5 %                 \[S.I.=\frac{P\times R\times T}{100}=\frac{1575\times 5\times 1}{100}\$78.75\]                 The amount after second year \[=\$1575+\$\] \[78.75=\$1653.75\]                 Therefore, the compound interest \[=A-P\]                 \[=\$1653.75-\$1500=\$153.75\]                                 Form the above discussion we conclude that
  • The principle for simple interest is same whereas it is different in the case of compound interest for every fixed interval of time.
  • The interest for simple interest is same whereas it is different in the case of compound interest for every fixed interval of time.  
                    Find the compound interest on $15,000 for 2 year at 8 % per annum.                 (a) Rs 2496                                          (b) Rs 2393                 (c) Rs 2293                                           (d) Rs 2593                 (e) None of these                     Answer: (a)                                 Explanation                                 Step 1: Principle for 1st year =$ 15,000, time (T) = 1 years, R = 8 % p.a.                 \[S.I.=\frac{P\times R\times T}{100}=\frac{15000\times 8\times 1}{100}\$1200\]                                                                        The amount after 1st year =$15,000 +$ 1,200 = $16,200                                 Step 2: Principle for the second year = Amount after 1st year =$ 16,200                 Time (T) = 1 year, R = 8 % P.a.                 \[S.I.=\frac{P\times R\times T}{100}=\frac{15000\times 8\times 1}{100}\$1296\]                 Amount after 2nd year =$16200 +$ 1296 = $17496                 Compound interest (C.I.) =Amount - Principle                 =$ 17496-$15000 =$ 2496       *       more...

*     Introduction                   The word triangle is derived from Greek word, triangle means three and hence it to a shape consisting three internal angles. Obviously the shape consists of sides. Hence, a triangle can be defined as a polygon having three sides.  

*     Basic Concepts of Triangles                  The general shape of a triangle is shown below:                                 The vertices of a triangle are denoted by the Capital letters of English alphabets.                 In the above figure \[\Delta ABC,\]the sides are AB, BC and CA.                   *      Altitude                 A Perpendicular drawn from a vertex to the opposite side is called the altitude of the triangle and denoted as h.     *      Some Basic Facts Related to Triangle
  • In any triangle, sum of any two sides is always greater than the 3rd side. i.e \[b+c>a\]or \[a+c>b\]or \[c+b>a.\]
  • The sum of all interior angles of a triangle is \[180{}^\circ \]
  • The exterior angle at any vertex of the triangle is equal to the sum of other two opposite angles.                
                  Proof: In \[\Delta ABC,a+b+c=180{}^\circ \]                 but,\[c+x=180{}^\circ \]   (Linear pair) \[c={{180}^{0}}-x\]                 Putting "c" in the above equation, we get                 \[a+b+180{}^\circ -x=180{}^\circ \Rightarrow a+b=x\]                    Therefore,\[~\Delta ACD=\Delta A+\Delta B\]     *      Types of Triangle                 Classification based on angles
  • If one angle of a triangle is right angle then it is called right angled triangle.
Note that the other two angles are acute.
  • From figure, \[\angle B=90{}^\circ \]and \[\angle A+\angle C=90{}^\circ .\]So, it is right-angled triangle
  • If all the angles of triangle are less than 90° then it is called acute-angled triangle.                
In the figure \[\angle A,\angle B\]and \[\angle C\]are acute angles.
  • If one angle of a triangle is more than 90° then it is called obtuse angled triangle. The other two angles are acute.  
  *      Equilateral Triangle A triangle in which all sides are equal is known as equilateral triangle.   *      Isosceles Triangle                 A triangle in which any two sides are equal is said to be and isosceles triangle.                 The angles opposite to the equal sides are equal.                 In the triangle given below, sides AB and AC are equal as well as \[\angle B\]and \[\angle C\]are also equal.                     *      Scalene Triangle                 A triangle in which all side are unequal is said to be scalene triangle.                 In scalene triangle all angles are different.                                 In the above given triangle all the sides of triangle denoted by a, b and c are unequal and angles x, y and z are also unequal.                   *       Pythagoras Theorem                 more...

*     Factorization of the Polynomials   Let us recall that an algebraic expression that is expressed as the product of two or more expressions & each of these is a factor of the given algebraic expression. The process of writing a given algebraic expression as the product of two or more factors is called factorization.   Some of the common methods of factorization of the algebraic expressions are as follows:
  •    Factorization by taking out a common factor.
  •    Factorization by using identities
  •    Factorization by regrouping the terms.  
  *      Factorization of the Algebraic Expression \[a{{x}^{2}}+bx+c\]   Step 1:   Find the product of constant term and coefficient of \[{{x}^{2}}\] i.e. ac.   Step 2:   Find factors of "ac".   Step 3:   Select the factors of 'ac' in such a way that addition or subtraction of factors must be equal to the coefficient of \[x\] i. e "b".   Step 4:   If the product 'ac' is positive then both the factors are either positive or negative.   Step 5:   If the product 'ac' is negative then the two factors of 'ac' will have different sign.         Find the factors of\[~{{x}^{2}}+9x+18\]                                 Solution:   Step 1: The product of constant term and coefficient of \[{{x}^{2}}\] is 18   Step 2: The product is positive. Therefore, both the factors of 18 will be either be positive or negative.   Step 3: But the coefficient of \[x\] is positive therefore, both the factors of 18 will be positive.   Step 4: Factors of 18 are \[1\times 18,2\times 9\] and \[3\times 6.\]One pair whose sum is 9 should betaken.   Step 5: The required number are 3 & 6. \[\therefore {{x}^{2}}+9x+18={{x}^{2}}+(6+3)x+18\] \[=(x+6)(x+3)\][By using identity \[(x+a)(x+b)=\]\[{{x}^{2}}+(a+b)x+ab]\] or \[{{x}^{2}}+9x+18={{x}^{2}}+6x+3x\text{ }+18\] \[=x(x+6)+3(x+6)=(x+6)(x+3).\] Taking out x from first two terms and 3 common from last two terms.                             Factorize: \[{{x}^{2}}-11x+30.\] (a)\[(x-6)(x-5)\]                                (b)\[(x-6)(x+5)\] (c)\[~(7{{x}^{2}}-6)(8x-9)\]                          (d) \[\left( 9{{x}^{2}}-62 \right)\left( 2x+3 \right)\]                 (e) None of these     Answer: (a) Explanation Let us find two numbers whose product is 30 & sum is \[(-11)\] Since, the product is positive, therefore, either both the numbers will be positive or negative. But the sum is negative hence, both the numbers will also be negative. Required factors of 30 are \[(-6)\] and \[(-5).\]                 \[\therefore {{x}^{2}}-11x+30={{x}^{2}}+\left\{ \text{(}-6\text{)}+(-5) \right\}\text{ }x+30\] \[={{x}^{2}}-6x-5x+30=x(x-6)-5(x-6)=(x-6)(x-5)\]         Factorize: \[{{x}^{2}}+x-12\]                 (a)\[(x+5)(x-3)\]                               (b) \[(x-9)(x-52)\] (c)\[(x+4)(x-3)\]                               (d) \[(7x+{{5}^{2}})(6x-7)\] (e) None of these     Answer: (c) Explanation To find two numbers whose product is (- 12) & sum is 1. Since the product is negative, one number will be positive & the other number will be negative. Since the sum is positive, the numerically greater of two numbers will be positive. So, the required factors more...

*     Algebraic identities   Abatement of equality which holds, for all values of the variable is called algebraic identities. Now we recall some important algebraic identities:
  • \[{{(a+b)}^{2}}={{a}^{2}}+2ab+{{b}^{2}}\]
  • \[{{(a-b)}^{2}}={{a}^{2}}-2ab+{{b}^{2}}\]
  • \[{{a}^{2}}-{{b}^{2}}=(a-b)(a+b)\]
  • \[{{(a+b+c)}^{2}}={{a}^{2}}+{{b}^{2}}+{{c}^{2}}+2ab+2bc+2ca\]
  • \[{{a}^{3}}+{{b}^{3}}={{(a+b)}^{3}}-3ab(a+b)\]or \[{{(a+b)}^{3}}={{a}^{3}}+{{b}^{3}}+3ab(a+b)\]
  • \[{{(a-b)}^{3}}={{a}^{3}}-{{b}^{3}}-3ab(a-b)\]
  • \[{{a}^{3}}+{{b}^{3}}={{(a+b)}^{3}}-3ab(a+b)\]or \[(a+b)({{a}^{2}}-ab+{{b}^{2}})\]
  • \[{{a}^{3}}-{{b}^{3}}={{(a-b)}^{3}}+3ab(a-b)\]or \[(a-b)({{a}^{2}}+ab+{{b}^{2}})\]
  • \[{{a}^{3}}+{{b}^{3}}+{{c}^{3}}-3abc=(a+b+c)\]\[({{a}^{2}}+{{b}^{2}}+{{c}^{2}}-ab-bc-ca)\]
               If \[(a+b+c)=0\]\[{{a}^{3}}+{{b}^{3}}+{{c}^{3}}=3abc\]       Simplify:  \[{{(2p+3q-+4r)}^{2}}+{{(2p-3q-4r)}^{2}}\] (a) \[2(4{{p}^{2}}+9{{q}^{2}}+16{{r}^{2}}-16rp)\] (b) \[-2(4{{p}^{2}}+9{{q}^{2}}+16{{r}^{2}}-16rp)\] (c) \[2(-4{{p}^{2}}+9{{q}^{2}}-16{{r}^{2}}+16rp)\] (d)\[~2(5{{p}^{2}}+9{{q}^{2}}-16{{r}^{2}}-98rp)\] (e) None of these     Answer: (a) Explanation    Let us first solve, \[{{\left[ 2p+3q+(-4r) \right]}^{2}}={{(2p)}^{2}}+{{(3q)}^{2}}\]\[+{{(-4r)}^{2}}+2(2p)(3q)+2(3q)(-4r)\] \[+2(-4r)(2p)=4{{p}^{2}}+4{{p}^{2}}+9{{q}^{2}}+16{{r}^{2}}\]\[+12pq-24qr-16rp..........(i)\] Now solve, \[~{{(2p-3q-4r)}^{2}}={{\left[ 2p+(-3q)+(-4r) \right]}^{2}}\] \[={{(2p)}^{2}}+{{(-3q)}^{2}}+{{(-4r)}^{2}}+2(2p)(-3q)+2(-3q)\]\[(-4r)+2(-4r)(2p)\] \[=4{{p}^{2}}+9{{q}^{2}}+16r2-12pq+24qr-16rp\text{ }.......\left( ii \right)\] Adding, (i) & (ii) we get, \[{{(2p+3a-4r)}^{2}}+{{(2p-3q-4r)}^{2}}\] \[=4{{p}^{2}}+9{{q}^{2}}+16{{r}^{2}}+12pq-24qr-16rp\]+ \[(4{{p}^{2}}+9{{q}^{2}}+16{{r}^{2}}-12pq+24qr-16rp)\]                 \[=4{{p}^{2}}+9{{q}^{2}}+16{{r}^{2}}+12pq-24qr-16rp+4{{p}^{2}}+9{{q}^{2}}\]    \[+16{{r}^{2}}-12pq+24qr-16rp\]                 \[=8{{p}^{2}}+18{{q}^{2}}+32{{r}^{2}}-32rp\]                 \[=2(4{{p}^{2}}+9{{q}^{2+}}16r2-16rp)\]             The expanded form of \[{{(2x+3y-5z)}^{2}}\] is:                 (a) \[4{{x}^{2}}+9{{y}^{2}}+25{{z}^{2}}+12xy-30yz-20zx\]                 (b) \[5{{x}^{2}}-6{{y}^{3}}+15{{z}^{3}}+12xy-36{{y}^{6}}+21x{{y}^{2}}\]                 (c) \[8{{a}^{2}}+{{a}^{3}}-{{c}^{2}}+7{{x}^{2}}+2{{c}^{2}}+9{{c}^{2}}y\]                 (d) \[1{{z}^{2}}-{{z}^{4}}-{{8}^{c}}-{{75}^{2}}+2{{c}^{2}}-98{{c}^{2}}\]                 (e) None of these                                   Answer: (a)                 Explanation \[{{(2x+3y-5z)}^{2}}={{(2x)}^{2}}+{{(3y)}^{2}}+{{(-5z)}^{2}}\]\[+2(2x)(3y)+2(3y)(-5z)+2(5z)(2x)\text{ }\]                                     Expand: \[{{(3a-b+4c)}^{2}}\] (a) \[~5{{x}^{2}}-6{{y}^{3}}+15{{z}^{3}}+12xy-36y+21xy\]                 (b) \[9{{a}^{2}}+{{b}^{2}}+16{{c}^{2}}-6ab-8bc+24ac\]                 (c) \[2{{x}^{2}}+7{{y}^{2}}+2{{z}^{2}}+xy+3yz+2zx\] (d) \[15a2+22{{b}^{2}}+2{{c}^{4}}+ab+4bc+102ca\] (e) \[5{{x}^{2}}-6{{y}^{3}}+15{{z}^{3}}+12xy-36y+21xy\]                                   Answer: (b)                 Explanation                 \[{{(3a-b+4c)}^{2}}={{(3a(-b)+4c)}^{2}}={{(3a)}^{2}}\]\[+{{(-b)}^{2}}+{{(4c)}^{2}}+2(3a)(-b)+2(-b)\] \[(4c)+2(4c)(3a)=9{{a}^{2}}+{{b}^{2}}+16{{c}^{2}}-6ab-8bc+24ac\]         Find the value of \[{{(3a+5b)}^{3}}.\] (a) \[27{{a}^{3}}+125{{b}^{3}}+135{{a}^{2}}b+225a{{b}^{2}}\] (b) \[27{{a}^{3}}-125{{b}^{3}}-135{{a}^{2}}b+2225a{{b}^{2}}\] (c) \[27{{a}^{2}}+155{{b}^{2}}-135{{a}^{2}}b-225{{a}^{2}}b\] (d) \[29{{a}^{2}}-156{{b}^{2}}-156{{a}^{2}}b-225{{a}^{4}}c\] (e) None of these                                   Answer: (a)                     Find the Cube of  \[x-2y.\] (a)\[~{{x}^{3}}+8{{y}^{2}}+6{{x}^{2}}y-12x{{y}^{3}}\]                      (b) \[{{x}^{3}}-8{{y}^{3}}-6{{x}^{2}}y+12x{{y}^{2}}\]v                 (c)\[{{x}^{2}}+87y+7xy-7xy\]                      (d) \[7x{{y}^{3}}-6x-74{{x}^{2}}y+2xy\]                 (e) None of these                     Answer: (b)                     Evaluate: \[{{\left( -6p+\frac{1}{3}q-r \right)}^{2}}\] (a) \[36{{p}^{2}}\frac{9}{1}{{p}^{2}}+{{5}^{2}}-4pq-\frac{2}{3}gr+12rp\]                 (b) \[36{{p}^{3}}\frac{9}{1}{{q}^{2}}+{{p}^{2}}+4qp-\frac{3}{2}qr+13rp\] (c)\[~36{{p}^{2}}+\frac{1}{9}{{q}^{2}}+{{r}^{2}}-4qp-\frac{2}{3}qr+12rp\]                              (d) \[36{{x}^{2}}-\frac{99}{8}{{s}^{2}}-{{s}^{2}}-4pq-\frac{2}{3}qr+14rp\] (e) None of these     Answer: (c)  

*     Operations on Algebraic Expression   Addition and subtraction of an algebraic expressions mean addition and subtraction of like terms.                   *      Addition of an Algebraic Expression For addition of algebraic expression we may follow any one of the following methods:                                   Row Method In this method, write all expression in a single row then arrange the terms to collect all like terms together and add it.                                   Column Method In this method, arrange each expression in such a way that each like term is placed one below to other in a column.       Add \[3x+2y+3z\]and \[2x-3y+4z\] Solution:                 \[(3x+2y+3z)+(2x-3y+4z)\]          \[=(3x+2x)+(2y-3y)+(3z+4z)=5x-y+7z\]  Column method                 \[3x+2y+3z\]                 \[\frac{+2x-3y+4z}{5x-y+7z}\]                   *      Subtraction of an Algebraic Expression For subtraction also you may follow any one of the following method                                   Row Method We arrange algebraic expression in a row and change the sign (from + to ?, ? or ? to +) of all terms which is to be subtracted. The two expression then added as above.                                   Column Method Arrange two expression in such a way that like terms are placed one below the other and change the sign (from + to ?,or ? to +) of algebraic expression which is to be subtracted.       Subtract  \[5{{a}^{2}}{{b}^{2}}+6{{a}^{2}}{{b}^{2}}+4\] from \[7{{a}^{2}}b-6{{a}^{2}}{{b}^{2}}+5\]                                 Solution:                 By row method,                 \[(7{{a}^{2}}b-6{{a}^{2}}{{b}^{2}}+5)-(5{{a}^{2}}b-6{{a}^{2}}{{b}^{2}}+4)\]                 \[=7{{a}^{2}}b-6{{a}^{2}}{{b}^{2}}+5-5{{a}^{2}}b-6{{a}^{2}}{{b}^{2}}-4\] Arrange like terms and add, we get \[=2{{a}^{2}}b-12{{a}^{2}}{{b}^{2}}+1\] By column method, \[7{{a}^{2}}b-6{{a}^{2}}{{b}^{2}}+5\] \[\frac{{{\underline{5a}}^{2}}b+6\underline{{{a}^{2}}}{{b}^{2}}+\underline{4}}{2{{a}^{2}}b-12{{a}^{2}}{{b}^{2}}+1}\]  

*     The value of an Algebraic Expression     Step 1:   If possible simplify the given algebraic expression.   Step 2:   Replace variable with given numerical value.   Step 3:   Simplify it.     Find the value of \[\frac{{{x}^{3}}+{{y}^{3}}+{{z}^{3}}-3xyz}{{{x}^{2}}+{{y}^{2}}+{{z}^{2}}-xy-yz-zx},\] lf \[x=1,y=2\] and \[z=-1.\] (a) 24                                                     (b) 14 (c) 7                                                       (d) 2 (e) None of these     Answer: (d) Explanation \[\frac{{{x}^{3}}+{{y}^{3}}+{{z}^{3}}-3xyz}{{{x}^{2}}+{{y}^{2}}+{{z}^{2}}-xy-yz-zx}=\frac{(x+y+z+)({{x}^{2}}+{{y}^{2}}+{{z}^{2}}-xy-yz-zx)}{({{x}^{2}}+{{y}^{2}}+{{z}^{2}}-xy-yz-zx)}\] \[=(x+y+z).\] Now putting the values of \[x,\text{ }y\]and \[z\] we get = 2             Find the value of \[4\text{ }xy\text{(}x-y\text{)}-6{{x}^{2}}\text{(}y-{{y}^{2}}\text{)}-3{{y}^{2}}(2{{x}^{2}}-x)+2xy(x-y)\] for \[x=5\]and \[y=13.\] (a) - 195                               (b) 2535 (c) - 2535                                             (d) 215 (e) None of these     Answer: (c)   Explanation \[4xy(x-y)-6{{x}^{2}}(y-{{y}^{2}})-3{{y}^{2}}(2{{x}^{2}}-x)+2xy(x-y)\]\[4{{x}^{2}}y-4x{{y}^{2}}-6{{x}^{2}}y+6{{x}^{2}}{{y}^{2}}-6{{y}^{2}}{{x}^{2}}+3x{{y}^{2}}+2{{x}^{2}}y-2x{{y}^{2}}\] After simplification, we get \[-\text{ }3x{{y}^{2}}=-3\times 5\times 13\times 13=-2535\]           The value of A, B, C, D, E, F, G, H and I for which \[(ABC)\times (DEF)=GHI\]                 (a) (6, 5, 7, 8, 2, 6, 1, 8, 4, 0)          (b) (7, 9, 5, 2, 6, 4, 8, 4, 0) (c) (4, 6, 7, 8, 5, 7, 0, 8, 9)               (d) (1, 0, 3, 7, 8, 4, 2, 1, 0)                 (e) None of these     Answer: (d) Explanation If we put the value of A, B, C, D, E, F, G, H and I from option D in the left hand side and right hand side of given expression, then it becomes zero.         Find the value of \[3{{x}^{3}}y+4{{x}^{y}}+2{{y}^{x}},\] if \[x=2\]\[x=2\]and \[y=-2.\]  (a) - 39                                                 (b) 39 (c) 13                                                     (d) Cannot be determined (e) None of these     Answer: (a)         Find the value of \[{{a}^{2}}+{{b}^{2}}+{{c}^{2}}-ab-bc-ca,\]if \[a=2b=-2\]and \[c=1.\] (a) 12                                                     (b) 1 (c) 13                                                     (d) 7 (e) None of these   Answer: (d)         Which one of the following options is the correct value or the expression \[\frac{axy+byz+cxy}{ax+by+cz+1},\] if \[a=1,b=2,c=-1,x=-1,y=2,z=3?\]   (a) 12                                                     (b) 10 (c) 13                                                     (d) 11 (e) None of these                                   Answer: (a)  

*     Introduction   We have discussed about the addition, subtraction, multiplication and division of the arithmetic expression into previous chapter. In this chapter, we will discuss about the operation on algebraic expression.     *     Algebraic Expression   It is the combination of constants and variables along with the fundamental operations \[(+,\,-,\,\,\times ,\,\,\div )\] Terms: It is the part of an algebraic expression which is separated by the sign of addition and subtraction. \[5{{x}^{4}}{{y}^{2}},35{{x}^{4}}{{y}^{2}}-13{{x}^{2}}y,6xy,-3\] is an algebraic expression having \[8{{x}^{3}}{{y}^{2}},-4{{x}^{2}}y,6xy,-3\] as its term.                   *      Like and Unlike Terms The terms having similar variable(s) are called like terms otherwise it is unlike. In an algebraic expression \[5{{x}^{4}}{{y}^{2}},-13{{x}^{2}}y+6xy-3-35{{x}^{4}}{{y}^{2}};5{{x}^{4}}{{y}^{2}},35{{x}^{4}}{{y}^{2}}\]are like terms and are unlike terms.     *      Types of Algebraic Expression   Monomials An algebraic expression which contains one term is called monomial. i.e. \[3x,4x,-xy,{{b}^{2}}a\] etc. are monomials.     Binomials An algebraic expression which contains two terms is called binomial. i.e. \[x+y,a-b,{{b}^{2}}a+{{a}^{2}}b\] etc. are binomials.   Trinomials An algebraic expression which contains three terms is called trinomial. i.e. \[\left( x+y+z \right),\text{ }\left( a+b+c \right),\text{ }\left( {{a}^{2}}+{{b}^{2}}+{{a}^{2}}{{b}^{2}} \right)\]etc. are trinomials. i.e. \[\left( a-b-c+d \right),\left( x+y+z-c \right)\]etc. are quadrimonials.     *      Polynomials                 An algebraic expression in which the variables have only non-negative integral power is called polynomial.
  • \[5{{a}^{3}}-4{{a}^{2}}+6a-3\]is a polynomial because powers of variable "a" are non-negative.
  • \[7{{a}^{3}}{{b}^{2}}-4{{a}^{2}}b+6ab-3\] is a polynomial in two variable.
  • \[4{{x}^{2}}+23{{x}^{3}}+37xy+45\]is a polynomial in two variable.
  • \[\sqrt{2x}+3{{x}^{2}}+5\]is not a polynomial because the power of first term is \[\frac{1}{2}\]which is not a non-negative integer.
  • \[4{{e}^{2}}+\frac{1}{6}e+2\sqrt{3}\]is a polynomial in one variable.
  *      Degree of Polynomial In case of one variable, the highest power of variable is the degree of polynomial e.g \[5{{x}^{4}}-4{{x}^{2}}+6x-3\] is a polynomial of degree 4. If polynomial is in the more than one variable then the highest sum of degree of the variables in each term is the degree of polynomial. e.g. \[8{{x}^{3}}{{y}^{2}}-4{{x}^{2}}y+6xy-3\]is a polynomial of degree 5.     *      Linear Polynomial A polynomial of one degree is called linear polynomial. \[p\left( x \right)=6x-3\] is a linear polynomial.     *      Quadratic Polynomial A polynomial of two degree is called quadratic polynomial. \[q(x)=4x2+3x+45\] is a quadratic polynomial.  

*     Negative Rational Number as Exponent   Let us consider 'a' be a positive rational number and \[x\left( i.e{{.}^{\frac{-m}{n}}} \right)\] be a negative rational exponent then it is defined as \[{{a}^{x}}\left( i.e.{{a}^{\frac{-m}{n}}} \right).\]       Find the value of \[{{4}^{\frac{-3}{2}}}\] and \[{{\left( 512 \right)}^{\frac{-2}{9}}}\] Solution: \[{{4}^{\frac{-3}{2}}}=\frac{1}{^{{{4}^{\frac{3}{2}}}}}=\frac{1}{^{\left( {{4}^{3}} \right)\frac{1}{2}}}=\frac{1}{{{\left( 64 \right)}^{\frac{1}{2}}}}=\frac{1}{8}\]and \[\frac{1}{{{\left( 512 \right)}^{\frac{-2}{9}}}}=\frac{1}{{{\left( {{512}^{2}} \right)}^{\frac{-2}{9}}}}\]\[=\frac{2}{\left( {{\left\{ {{\left( {{2}^{9}} \right)}^{2}} \right\}}^{\frac{1}{9}}} \right)}=\frac{1}{^{_{2}\cancel{9}\times 2\times \frac{1}{\cancel{9}}}}=\frac{1}{4}\]             Evaluate : \[{{\left( \frac{4}{9} \right)}^{\frac{3}{2}}}\times {{\left( \frac{4}{9} \right)}^{\frac{1}{2}}}\] (a) \[{{\left( \frac{4}{9} \right)}^{2}}\]                                    (b) \[{{\left( \frac{81}{16} \right)}^{4}}\] (c) \[{{\left( \frac{4}{9} \right)}^{4}}\]                                     (d) \[\frac{4}{27}\]                 (e) None of these     Answer: (a) Solution: \[{{\left( \frac{4}{9} \right)}^{\frac{3}{2}}}\times {{\left( \frac{4}{9} \right)}^{\frac{1}{2}}}={{\left( \frac{4}{9} \right)}^{\frac{3}{2}+\frac{1}{2}}}={{\left( \frac{4}{9} \right)}^{\frac{3+1}{2}}}={{\left( \frac{4}{9} \right)}^{\frac{\cancel{4}}{\cancel{2}}}}={{\left( \frac{4}{9} \right)}^{2}}\]         Evaluate: \[{{(27)}^{\frac{6}{5}}}\div {{(27)}^{\frac{1}{5}}}\] (a) \[5\times {{3}^{3}}\]                                                (b) \[1\times {{3}^{3}}\] (c) \[2\times {{3}^{3}}\]                                                (d) \[7\times {{3}^{3}}\] (e) None of these   Answer: (b) Solution: \[{{(27)}^{\frac{6}{5}}}\div {{(27)}^{\frac{1}{5}}}={{(27)}^{\frac{6}{5}-\frac{1}{5}}}={{(27)}^{\frac{5}{5}}}=27={{3}^{3}}\]         Evaluate: \[\frac{{{\left( 27 \right)}^{\frac{-2}{3}}}\times {{\left( 81 \right)}^{\frac{5}{4}}}}{{{\left( \frac{1}{3} \right)}^{-3}}}\] (a) 1                                                       (b) 2 (c) 3                                                       (d) 4 (e) None of these     Answer: (a) Solution: \[\frac{{{\left( 27 \right)}^{\frac{-2}{3}}}\times {{\left( 81 \right)}^{\frac{5}{4}}}}{{{\left( \frac{1}{3} \right)}^{-3}}}=\frac{{{3}^{\cancel{3}\times \left( \frac{2}{\cancel{3}} \right)}}\times {{3}^{\cancel{4}\times \frac{5}{\cancel{4}}}}}{{{3}^{3}}}=\frac{{{3}^{-2}}\times {{3}^{5}}}{{{3}^{3}}}=\frac{{{3}^{-2+5}}}{{{3}^{3}}}=\frac{{{3}^{3}}}{{{3}^{3}}}=1\]         Evaluate:  \[{{\left[ {{\left( \frac{36}{25} \right)}^{\frac{3}{2}}} \right]}^{\frac{5}{3}}}\] (a) \[\frac{7776}{3125}\]                                              (b) 1 (c) \[\frac{75}{31}\]                                                         (d) 2 (e) None of these     Answer: (a) Solution:                 \[{{\left( \frac{36}{25} \right)}^{\frac{\cancel{3}}{2}\times \frac{5}{\cancel{3}}}}{{\left( \frac{36}{25} \right)}^{\frac{5}{2}}}={{\left( \frac{6}{2} \right)}^{\cancel{2}\times \frac{5}{\cancel{2}}}}{{\left( \frac{6}{2} \right)}^{5}}=\frac{7776}{3125}\]                       Evaluate:  \[{{\left[ {{\left\{ {{\left( 625 \right)}^{-\frac{1}{2}}} \right\}}^{\frac{1}{4}}} \right]}^{2}}\] (a) 2                                                       (b) 3 (c) 4                                                       (d) 5 (e) None of these     Answer: (d) Solution \[{{\left( 625 \right)}^{-\frac{1}{\cancel{2}}\times \left( -\frac{1}{4} \right)\times \cancel{2}}}={{\left( 625 \right)}^{\frac{1}{4}}}={{\left( 5 \right)}^{\cancel{4}\times \frac{1}{4}=5}}\]         Evaluate: \[{{64}^{\frac{2}{3}}}\times {{27}^{\frac{2}{3}}}\] (a) 144                                                  (b) 12 (c) 4                                                       (d) 3 (e) None of these     Answer: (a) Solution: \[{{\left( 64\times 27 \right)}^{\frac{2}{3}}}={{\left( {{4}^{3}}\times {{3}^{3}} \right)}^{\frac{2}{3}}}={{\left( 4\times 3 \right)}^{\cancel{3}\times \frac{2}{\cancel{3}}}}=16\times 9=144\]         Evaluate: \[{{\left[ {{\left\{ {{\left( \frac{1}{x} \right)}^{-12}} \right\}}^{\frac{1}{4}}} \right]}^{-\frac{2}{3}}}\] (a) \[\frac{1}{x}\]                                                          (b) \[\frac{1}{{{x}^{2}}}\] (c) \[\frac{1}{{{x}^{3}}}\]                                              (d)\[\frac{1}{{{x}^{4}}}\] (e) None of these     Answer: (b)         Evaluate: \[{{\left[ {{\left( 729 \right)}^{\frac{-5}{3}}} \right]}^{-\frac{1}{2}}}\] (a) 243                                                  (b) 81 (c) 27                                                     (d) 9 (e) None of these     Answer: (a) Solution: \[{{\left( 729 \right)}^{\frac{-5}{3}\times \left( \frac{-1}{2} \right)}}={{\left( 9 \right)}^{^{\cancel{3}\times \left( \frac{-5}{\cancel{3}} \right)\left( \frac{-1}{2} \right)}}}={{9}^{\frac{5}{2}}}={{3}^{\cancel{2}{{\times }^{\frac{5}{\cancel{2}}}}}}={{3}^{5}}=243\]         Find the value of\[x\], if \[{{\left( \sqrt{6} \right)}^{x-2}}=1.\] (a) 1                                                       (b) 2                 (c) 3                                                       (d) 4 (e) None of these     Answer: (b)   Solution: We can more...


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