Find the range of the function y = 4 x-3 times 2 x-3

Find the range of the function y = 4 x-3 times 2 x-3

Let 2 ^ x = t, then t > 0
y=4^x-3*2^x+3
=(2^x)^2-3*2^x+3
=t^2-3t+3…… Where t > 0
=(t-3/2)^2+3/4
Because (T-3 / 2) ^ 2 is greater than or equal to 0,
So y ≥ 3 / 4