Question

If ${20}^{-x}=\frac{1}{7}$, then the value of ${\left(20\right)}^{2x}$ is-

• A. $\frac{1}{49}$
• B. $7$
• C. $49$
• D. $1$

Answer 1

The correct option is C $49$

Given that,

${20}^{-x}=\frac{1}{7}$

$⟹\frac{1}{{20}^x}=\frac{1}{7}$

$⟹{20}^x=7$

$\therefore {20}^{2x}={\left({20}^x\right)}^2=7^2=49$(Ans)

Option C is correct.