Question

8.2²ₓ +7.2ₓ-1=0 (obs os x sao elevados também)

Answer 1

$8.2^{2x}+7.2^x-1=0\\ 8.(2^{x})^2+7.2^x-1=0\\ 2^x=y\\ 8y^2+7y-1=0\\ x'=\frac{1}{8} \hspace{0.2cm}x''=-1\\ Entao\\ 2^x=\frac{1}{8}\\ 2^x=2^{-3}\\ x=-3$