Question

$2^{x} + 2^{x+2} leq 20$

Answer 1

$2^x+2^{x+2} leq 20 \ 2^x+4*2^x leq 20 \ 5*2^x leq 20 \ 2^x leq 4 \ 2^x leq 2^2 \ x leq 2$