4^{x^2} = 2^x
(1/4)^x = (1/64)
5^x = 5^-6
5 ^(x-3) = 1/5
9^{-x+15} = 27^x
3^-x = 81
x= 6
x = -4
x= 1/2 , x = 0
x = 2
x = -6
x = 3
