Equations-And-Inequalities Question 61

Question: If $ {{(\sqrt{2})}^{x}}+{{(\sqrt{3})}^{x}}={{(\sqrt{13})}^{x/2}}, $ then the number of values of x is

Options:

A) 2

B) 4

C) 1

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

  • [c] $ {2^{x/2}}+{3^{x/2}}={{(\sqrt{13})}^{x/2}} $
    $ \Rightarrow {{( \frac{2}{\sqrt{13}} )}^{x/2}}+{{( \frac{3}{\sqrt{13}} )}^{x/2}}=1 $ Which is of the form $ {{\cos }^{x/2}}\alpha +{{\sin }^{x/2}}\alpha =1. $
    $ \therefore ,\frac{x}{2}=2. $