Question

2^(2+x) - 2^(2-x)=15

Answer 1

$2^{2+x}-2^{2-x}=15;\ 4(2^x-2^{-x})=15;\ 2^x=t;\ 4(t-frac{1}{t})=15;\ frac{t^2-1}{t}=frac{15}{4};\ 4t^2-15t-4=0; \ left[ begin{gathered} t=4\ t=-frac{1}{4}\ end{gathered} \ x=2;$