Question

If $2^x+2^{x+2}=40$, then the value of $x$ is

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

Answer: (C)

$3$

Given, $2^x+2^{x+2}=40\Rightarrow 2^x+2^2{2}^x=40\Rightarrow 2^x+\left(4\right)2^x=40\Rightarrow \left(5\right)2^x=40\Rightarrow 2^x=8\Rightarrow 2^x=2^3$

So, $x=3$