Question

Resolva:
4^(x+1) - 2^(x+1) - 56=0

Answer 1

4^ (x + 1) - 2^ (x + 1) - 56 = 0 
2^2 (x + 1) - 2^ (x + 1) =56 
2^(2x + 2) - 2^ (x + 1) =56 
2^(2x).2^2-2^x.2=8.7 
2^(2x).2-2^x=4.7 

2^x=y 

2y²-y-28=0 
y=[1+-15]/4 
y'=16/4=4 

2^x=y 
2^x=4 
x=2