f(x+1)=x^2+2x+2,求f(x)的解析式设y=x+1
x=y-1
f(x+1)=x^2+2x+2
f(y)=(y-1)^2+2(y-1)+2
f(y)=y^2-2y+1+2y-2+2
f(y)=y^2+1
f(x)=x^2+1f(y)=y^2-2y+1+2y-2+2怎样的来?