y=4^x-3.2^x+3
= (2^x)^2 - 3×2^x + 3
= (2^x-3/2)^2 + 3/4
x∈[1,2]
2^x∈[2,4]
2^x-3/2∈[1/2,5/2]
(2^x-3/2)^2 ∈[1/4,25/4]
(2^x-3/2)^2 + 3/4∈[1,7]
值域[1,7]
y=4^x-3.2^x+3
= (2^x)^2 - 3×2^x + 3
= (2^x-3/2)^2 + 3/4
x∈[1,2]
2^x∈[2,4]
2^x-3/2∈[1/2,5/2]
(2^x-3/2)^2 ∈[1/4,25/4]
(2^x-3/2)^2 + 3/4∈[1,7]
值域[1,7]