f(2-1经)=4X^2+3X-1,对吗?
设t=2X-1,X=1/2(t+1),
f(t)=4*1/4(t+1)^2+3/2(t+1)-1
=t^2+7/2t+3/2,
∴f(x)=X^2+3.5x+1.5.已知f(x+1)=x2-x+3求fx设t=X+1,X=t-1,f(t)=(t-1)^2-(t-1)+3=t^2-3t+5,∴f(x)=X^2-3X+5.