(1)9x+6x²-3(x-2/3x-2²),其中X=-2
=9x+6x²-3x+2x+12
=6x²+8x+12 其中X=-2
=6*(-2)²+8*(-2)+12
=24-16+12
=20
(2)1/4(-4x²-2x-8)-(1/2x-1),其中X=1/2
=-x²-1/2x-2-1/2x+1
=-x²-x-1 其中X=1/2
=-(1/2)²-1/2-1
=-1/4-1/2-1
=-7/4
(3)（5a²-3b²）+（a²+b²)-（5a²+3b²）,其中a=-1,b=1
=5a²-3b²+a²+b²-5a²-3b²
=a²-5b² 其中a=-1,b=1
=(-1)²-5*1²
=1-5
=-4
(4)2(a²b+ab²)-2（a²b-1)-2ab²-2,其中a=-2,b=2
=2a²b+2ab²-2a²b+2-2ab²-2
=0
3．3ab-4ab+8ab-7ab+ab=ab．
4．7x-(5x-5y)-y=_2x+4y_____．
5．23a^3bc^2-15ab^2c+8abc-24a^3bc^2-8abc=-a^3bc^2-15ab^2c．
6．-7x^2+6x+13x^2-4x-5x^2=x^2+2x______．
7．2y+(-2y+5)-(3y+2)＝3-3y______．
11．(2x^2-3xy+4y^2)+(x^2+2xy-3y^2)=3x^2-xy+y^2______．
12．2a-(3a-2b+2)+(3a-4b-1)=2a-2b-3______．
13．-6x^2-7x^2+15x^2-2x^2＝0______．
14．2x-(x+3y)-(-x-y)-(x-y)＝__x-y____．
15．2x+2y-[3x-2(x-y)]=x______．