3ab-4ab+8ab-7ab+ab=______．
4．7x-(5x-5y)-y=______．
5．23a3bc2-15ab2c+8abc-24a3bc2-8abc=______．
6．-7x2+6x+13x2-4x-5x2=______．
7．2y+(-2y+5)-(3y+2)＝______．
11．(2x2-3xy+4y2)+(x2+2xy-3y2)=______．
12．2a-(3a-2b+2)+(3a-4b-1)=______．
13．-6x2-7x2+15x2-2x2＝______．
14．2x-(x+3y)-(-x-y)-(x-y)＝______．
16．2x+2y-[3x-2(x-y)]=______．
17．5-(1-x)-1-(x-1)=______．
18．( )+(4xy+7x2-y2)=10x2-xy．
19．(4xy2-2x2y)-( )=x3-2x2y+4xy2+y3．
21．已知A=x3-2x2+x-4,B=2x3-5x+3,計(jì)算A+B=______．
22．已知A=x3-2x2+x-4,B=2x3-5x+3,計(jì)算A-B=______．
23．若a=-0.2,b=0.5,代數(shù)式-(|a2b|-|ab2|)的值為______．
25．一個多項(xiàng)式減去3m4-m3-2m+5得-2m4-3m3-2m2-1,那么這個多項(xiàng)式等于______．
26．-(2x2-y2)-[2y2-(x2+2xy)]=______．
27．若-3a3b2與5ax-1by+2是同類項(xiàng),則x=______,y=______．
28．(-y+6+3y4-y3)-(2y2-3y3+y4-7)＝______．
29．化簡代數(shù)式4x2-[7x2-5x-3(1-2x+x2)]的結(jié)果是______．
30．2a-b2+c-d3=2a+( )-d3=2a-d3-( )=c-( )．
31．3a-(2a-3b)+3(a-2b)-b=______．
32．化簡代數(shù)式x-[y-2x-(x+y)]等于______．
33．[5a2+( )a-7]+[( )a2-4a+( )]=a2+2a+1．
34．3x-[y-(2x+y)]=______．
35．化簡|1-x+y|-|x-y|(其中x＜0,y＞0)等于______．
36．已知x≤y,x+y-|x-y|=______．
37．已知x＜0,y＜0,化簡|x+y|-|5-x-y|=______．
38．4a2n-an-(3an-2a2n)＝______．
39．若一個多項(xiàng)式加上-3x2y+2x2-3xy-4得
2x2y+3xy2-x2+2xy,
則這個多項(xiàng)式為______．
40．-5xm-xm-(-7xm)+(-3xm)=______．
41．當(dāng)a=-1,b=-2時,
[a-(b-c)]-[-b-(-c-a)]＝______．
43．當(dāng)a=-1,b=1,c=-1時,
-[b-2(-5a)]-(-3b+5c)＝______．
44．-2(3x+z)-(-6x)+(-5y+3z)=______．
45．-5an-an+1-(-7an+1)+(-3an)＝______．
46．3a-(2a-4b-6c)+3(-2c+2b)=______．
48．9a2+[7a2-2a-(-a2+3a)]=______．
50．當(dāng)2y-x=5時,5(x-2y)2-3(-x+2y)-100=______．