已知f(2x+3)=x^2-2x-3，则f(x-1)=___

已知f(2x+3)=x^2-2x-3，
设u-1=2x+3,则x=(u-4)/2
f(u-1)=[(u-4)/2]^2-2*(u-4)/2-3=u^2/4-3u+5
则f(x-1)=x^2/4-3x+5

f(2x+3)=x^2-2x-3
令t=2x+3
=>x=(t-3)/2
x-1=(t-5)/2

f(x-1)=(t-5)^2/4-(t-5)-3
=t^2/4-7t/2+33/4
即f(x-1)=x^2/4-7x/2+33/4

4分之一的（X方-12X+20）不懂发信息