2(a²b+ab²-ab)-2(a²b-1)-2ab²+3ab,其中a＝﹣2,b＝2
=2a²b+2ab²-2ab-2a²b+2-2ab²+3ab
=ab+2
=(-2)×2+2
=-4+2
=-2
已知(a-2)²+|b+1|=0,求5ab²－[a²b－2(2ab²－a²b)]的值,
∵(a-2)²+|b+1|=0,
∴ a-2=0 b+1=0
a=2 b=-1
5ab²－[a²b－2(2ab²－a²b)]
=5ab²-a²b+4ab²-2a²b
= 9ab²-3a²b
=9×2×(-1)²-3×2²×(-1)
=18+12
=30
解方程
2分之y-6分之5y+11=1+3分之2y-4
3y-(5y+11)=6+2(2y-4)
3y-5y-11=6+4y-8
-2y-4y=-2+11
-6y=9
y=-3/2
y=-1.5