已知Ia-2I+(b+1)=0求5ab^2-{2a^b-[3ab^2-(4ab^2-2a^2b)]}的值
问题描述：
已知Ia-2I+(b+1)=0求5ab^2-{2a^b-[3ab^2-(4ab^2-2a^2b)]}的值
答
2(a-2)^2 (b 1)^2=0,
a-2=0 a=2
b 1=0 b=-1
3a^2 b ab^2-3a^2 b 5ab ab^2-4ab 1/2a^2b
=1/2a^2b 2ab^2 ab
=1/2x4x-1 2x2x1 2x-1
=-2 4-2
=0