10th Class Mathematics Solved Paper - Mathematics-2016 Outside Delhi Set-III

  • question_answer
    Three consecutive natural numbers are such that the square of the middle number exceeds the difference of the squares of the other two by 60. Find the numbers.

    Answer:

    Let the three consecutive natural numbers be \[x,x+1\] and \[x+2\].
    According to the given condition,
    \[\therefore {{(x+1)}^{2}}-[{{(x+2)}^{2}}-{{x}^{2}}]=60\]
    \[{{x}^{2}}+1+2x-[(x+2-x)(x+2+x)]=60\]
                    \[{{x}^{2}}+2x+1-[2(2+2x)]=60\]
                          \[{{x}^{2}}+2x+1-4-4x=60\]
                                       \[{{x}^{2}}-2x-63=0\]
                               \[{{x}^{2}}-9x+7x-63=0\]
                               \[x(x-9)+7(x-9)=0\]
                                       \[(x+7)(x-9)=0\]
    \[\therefore x=9\] or \[-7\]
    \[\therefore x=9\]                        (neglect \[x=-7\])
    \[\therefore \] Number are 9, 10, 11.         


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