l a+1l+l b-2l+l c+3l=0,
那么a+1=0 b-2=0 c+3=0
a= -1 b=2 c= -3
(a-1)(b+2)(c-2)
=(-1-1)×(2+2)×(-3-2)
= -2×4×(-5)
=40