f（x+2）=3x平方+2x-1，求f（x-1）麻煩給個答案

f（x+2）=3x^2+2x-1
設x+2=t
x=t-2
f（t）=3（t-2）^2+2（t-2）-1
=3（t^2-4t+4）+2t-4-1
=3t^2-12t+12+2t-5
=3t^2-10t+7
f（x）=3x^2-10x+7
f（x-1）=3（x-1）^2-10（x-1）+7