Show that 4/2^x = 2^2-x and hence or otherwise solve for x in the equation 2^x +2^x-2 =5

4 = 2^2

4/(2^x) = (2^2)/(2^x) = 2^(2-x)

Now, just solve the equation. Hint: 2^(x-2) = 2^x / 4