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  4. Quantitative Aptitude
  5. Power, Surds And Indices

Railways Quantitative Aptitude Power, Surds And Indices Sample Paper Surds Indices Sample Test Paper-4

  • question_answer
    Value of \[\frac{991\times 991\times 991+9\times 9\times 9}{991\times 991-991\times 9+9\times 9}\] is

    A)  991                 

    B)  9        

    C)  1000               

    D)  \[991\times 9\]

    Correct Answer: C

    Solution :

    [c] \[\frac{{{(991)}^{3}}+{{(9)}^{3}}}{{{(991)}^{2}}-991\times 9+{{(9)}^{2}}}\] As \[\frac{{{a}^{3}}+{{b}^{3}}}{{{a}^{2}}-ab+{{b}^{2}}}=\frac{\left( a+b \right)\left( {{a}^{2}}-ab+{{b}^{2}} \right)}{\left( {{a}^{2}}-ab+{{b}^{2}} \right)}\] = a + b \[\therefore \] \[991+9=1000\]


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