已知f(x+1)=x2-2x,求f(3-2x)

问题描述:

已知f(x+1)=x2-2x,求f(3-2x)

令x+1=tx=t-1f(t)=(t-1)^2-2(t-1)=t^2-2t+1-2t+2=t^2-4t+3f(3-2x)=(3-2x)^2-4(3-2x)+3=4x^2-12x+9+8x-12+3=4x^2-4x+12