Quantitative Aptitude Ques 412

Question: Simplify for the value of x. $ {{[{{[\sqrt[7]{({x^{-4/7}})}]}^{7/3}}]}^{21}}=\frac{1}{16} $

Options:

A) 1

B) 2

C) 3

D) 4

Show Answer

Answer:

Correct Answer: B

Solution:

  • $ {{{{{[\sqrt[7]{{x^{-4/7}}}]}^{7/3}}}}^{21}}=\frac{1}{16} $

$ \Rightarrow $ $ {{{{{[{{({x^{-4/7}})}^{1/7}}]}^{7/3}}}}^{21}}=\frac{1}{16} $

$ \Rightarrow $ $ {{[{x^{-4/7}}]}^{1/3\times ,}}^{21}=\frac{1}{16} $

$ \Rightarrow $ $ {x^{-4}}={16^{-1}}={2^{-4}} $
$ \Rightarrow $ $ x=2 $