JEE Main & Advanced Mathematics Binomial Theorem and Mathematical Induction Question Bank Binomial theorem for any index

  • question_answer
    The approximate value of \[{{(7.995)}^{1/3}}\]correct to four decimal places is                  [MNR 1991; UPSEAT 2000]

    A) 1.9995

    B) 1.9996

    C) 1.9990

    D) 1.9991

    Correct Answer: A

    Solution :

    \[{{(7.995)}^{1/3}}={{(8-0.005)}^{1/3}}={{(8)}^{1/3}}\] \[{{\left[ 1-\frac{0.005}{8} \right]}^{1/3}}\] \[=2\,\,\left[ 1-\frac{1}{3}\times \frac{0.005}{8}+\frac{\frac{1}{3}\left( \frac{1}{3}-1 \right)}{2+1}{{\left( \frac{0.005}{8} \right)}^{2}}+..... \right]\] \[=2\,\left[ 1-\frac{0.005}{24}-\frac{\frac{1}{3}\times \frac{1}{3}}{1}\times {{\frac{(0.005)}{8}}^{2}}+..... \right]\] \[=2(1-0.000208)=2\times 0.999792=1.9995\]


You need to login to perform this action.
You will be redirected in 3 sec spinner