f(x)=4^x+3.2^x+2=64 (tanda sesudah ^ adalah pangkatnya)

f(x) = 4^(x+3) . 2^(x+2) = 64
f(x) = (2^2)^(x+3) . 2^(x+2) = 2^6
f(x) = 2^(2(x+3)) . 2^(x+2) = 2^6
f(x) = 2^(2x+6) .2^(x+2) = 2^6
f(x) = 2^((2x+6)+(x+2)) = 2^6
f(x) = 2^(2x+6+x+2) = 2^6
f(x) = 2^(3x+8) = 2^6

3x + 8 = 6
3x = 6 - 8
3x = -2
x = -2/3

Jadi x = -2/3