10th Class Mathematics Quadratic Equations Question Bank Quadratic Equations

  • question_answer
    The denominator of a fraction is one more than twice the numerator. If the sum of the A r. fraction and its reciprocal is \[2\frac{16}{21},\] find the fraction.                    

    A)  \[\frac{3}{7}\]                       

    B)  \[\frac{7}{3}\]                       

    C)  \[\frac{4}{3}\]                       

    D)  \[\frac{3}{4}\]

    Correct Answer: A

    Solution :

    Let the fraction be \[\frac{x}{y}\]. According to the question, \[y=2x+1\]                              ....(1) Also,   \[\frac{x}{y}+\frac{y}{x}=2\frac{16}{21}=\frac{58}{21}\] \[\Rightarrow \]  \[\frac{x}{2x+1}+\frac{2x+1}{x}=\frac{58}{21}\]  (From(1)) \[\Rightarrow \]  \[\frac{{{x}^{2}}+4{{x}^{2}}+1+4x}{x(2x+1)}=\frac{58}{21}\] \[\Rightarrow \] \[105{{x}^{2}}+84x+21=116{{x}^{2}}+58x\] \[\Rightarrow \]            \[(x-3)\,(11x+7)=0\] \[\Rightarrow \]  \[x=3,\]  or  \[x=-\frac{7}{11}\]  (Not possible) \[\therefore \]   \[y=7\]  \[\therefore \]Required fraction \[=\frac{3}{7}\]


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