4 to the power of X - 2 to the power of X + 1 - 8 = 0

4 to the power of X - 2 to the power of X + 1 - 8 = 0

4^x-2^(x+1)-8=0
(2^2)^x-2*2^x-8=0
(2^x)^2-2*2^x-8=0
(2^x-4)(2^x+2)=0
Because 2 ^ x + 2 > 0
SO 2 ^ x-4 = 0
2^x=4
x=2