Binomial Theorem And Its Simple Applications Question 127

Question: If the $ 6^{th} $ term in the expansion of $ {{( \frac{1}{{x^{8/3}}}+x^{2}{\log_{10}}x )}^{8}} $ is 5600, then x equals

Options:

A) 1

B) $ {\log_{e}}10 $

C) 10

D) x does not exist

Show Answer

Answer:

Correct Answer: C

Solution:

  • [c] It is given that $ 6^{th} $ term in the expansion of $ {{( \frac{1}{{x^{8/3}}}+x^{2}{\log_{10}}x )}^{8}} $

$ ^{8}C_5{{(x^{2}log_{10}x)}^{5}}{{( \frac{1}{{x^{8/3}}} )}^{3}}=5600 $

Or $ 56x^{10}{{(log_{10}x)}^{5}}\frac{1}{x^{8}}=5600 $ Or $ x^{2}{{(log_{10}x)}^{5}}=100 $ Or

$ x^{2}{{(log_{10}x)}^{5}}=10^{2}{{(log_{10}10)}^{5}} $ Or $ x=10 $