f^2(x)=（log2x）^2+4（log2x）+4f(x^2)=2+log2x^2=2+2(log2x)y=(log2x）^2+4（log2x）+4+2+2(log2x) =(log2x）^2+6(log2x)+6 =[(log2x）+3]^2-3x∈[1,9] ∴log2x∈[0,2log(2)(3)]（楼主题没写错吧,会不会是∈...