Question

If $2^x-2^{x-1}=4$ then $x^x$ is equals to

• A. $7$
• B. $3$
• C. $27$
• D. None of these

Answer 1

The correct option is C $27$

$2^x-2^{x-1}=4$

$2^x-2^x{2}^{-1}=4$

$2^x(1-\frac{1}{2})=2^{x-1}=4=2^2$

$\therefore$ $x-1=2$

$\text{from this we get}$ $x=3$

$x^x=3^3=27$