北师大版七年级数学上合并同类项练习题.docx
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北师大版七年级数学上合并同类项练习题.docx
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北师大版七年级数学上合并同类项练习题
合并同类项练习题
1.3ab-4ab+8ab-7ab+ab=
2.7x-(5x-5y)-y=
3.23a3bc2-15ab2c+8abc-24a3bc2-8abc=______.
4.-7x2+6x+13x2-4x-5x2=______.
5.2y+(-2y+5)-(3y+2)=______.
6.(2x2-3xy+4y2)+(x2+2xy-3y2)=______.
7.2a-(3a-2b+2)+(3a-4b-1)=______.
8.-6x2-7x2+15x2-2x2=______.
9.2x-(x+3y)-(-x-y)-(x-y)=______.
10.2x+2y-[3x-2(x-y)]=______.
11.5-(1-x)-1-(x-1)=______.
12.()+(4xy+7x2-y2)=10x2-xy.
13.(4xy2-2x2y)-()=x3-2x2y+4xy2+y3.
14.已知A=x3-2x2+x-4,B=2x3-5x+3,计算A+B=______.
15.已知A=x3-2x2+x-4,B=2x3-5x+3,计算A-B=______.
16.若a=-0.2,b=0.5,代数式-(|a2b|-|ab2|)的值为______.
17.一个多项式减去3m4-m3-2m+5得-2m4-3m3-2m2-1,那么这个多项式等于______.
18.-(2x2-y2)-[2y2-(x2+2xy)]=______.
19.若-3a3b2与5ax-1by+2是同类项,则x=______,y=______.
20.(-y+6+3y4-y3)-(2y2-3y3+y4-7)=______.
21.化简代数式4x2-[7x2-5x-3(1-2x+x2)]的结果是______.
22.2a-b2+c-d3=2a+()-d3=2a-d3-()=c-().
23.3a-(2a-3b)+3(a-2b)-b=______.
24.化简代数式x-[y-2x-(x+y)]等于______.
25.[5a2+()a-7]+[()a2-4a+()]=a2+2a+1.
26.3x-[y-(2x+y)]=______.
27.化简|1-x+y|-|x-y|(其中x<0,y>0)等于______.
28.已知x≤y,x+y-|x-y|=______.
29.已知x<0,y<0,化简|x+y|-|5-x-y|=______.
30.4a2n-an-(3an-2a2n)=______.
31.若一个多项式加上-3x2y+2x2-3xy-4得
32、2x2y+3xy2-x2+2xy,则这个多项式为______.
33.-5xm-xm-(-7xm)+(-3xm)=______.
34.当a=-1,b=-2时,[a-(b-c)]-[-b-(-c-a)]=______.
35.当a=-1,b=1,c=-1时,-[b-2(-5a)]-(-3b+5c)=______.
36.-2(3x+z)-(-6x)+(-5y+3z)=______.
37.-5an-an+1-(-7an+1)+(-3an)=______.
38.3a-(2a-4b-6c)+3(-2c+2b)=______.
39.9a2+[7a2-2a-(-a2+3a)]=______.
40.当2y-x=5时,5(x-2y)2-3(-x+2y)-100=______.
41.(4x2-8x+5)-(x3+3x2-6x+2).
42.(0.3x3-x2y+xy2-y3)-(-0.5x3-x2y+0.3xy2).
43.-{2a2b-[3abc-(4ab2-a2b)]}.
44.(5a2b+3a2b2-ab2)-(-2ab2+3a2b2+a2b).
45.(x2-2y2-z2)-(-y2+3x2-z2)+(5x2-y2+2z2).
46.(3a6-a4+2a5-4a3-1)-(2-a+a3-a5-a4).
47.(4a-2b-c)-5a-[8b-2c-(a+b)].
48.(2m-3n)-(3m-2n)+(5n+m).
49.(3a2-4ab-5b2)-(2b2-5a2+2ab)-(-6ab).
50.xy-(2xy-3z)+(3xy-4z).
51.(-3x3+2x2-5x+1)-(5-6x-x2+x3).
52.3x-(2x-4y-6x)+3(-2z+2y).
53.(-x2+4+3x4-x3)-(x2+2x-x4-5).
54.若A=5a2-2ab+3b2,B=-2b2+3ab-a2,计算A+B.
55.已知A=3a2-5a-12,B=2a2+3a-4,求2(A-B).
56.2m-{-3n+[-4m-(3m-n)]}.
57.5m2n+(-2m2n)+2mn2-(+m2n).
58.4(x-y+z)-2(x+y-z)-3(-x-y-z).
59.2(x2-2xy+y2-3)+(-x2+y2)-(x2+2xy+y2).
60.2(a2-ab-b2)-3(4a-2b)+2(7a2-4ab+b2).
61.4x-2(x-3)-3[x-3(4-2x)+8].
(四)将下列各式先化简,再求值
62.已知a+b=2,a-b=-1,求3(a+b)2(a-b)2-5(a+b)2×(a-b)2的值.
63.已知A=a2+2b2-3c2,B=-b2-2c2+3a2,C=c2+2a2-3b2,求(A-B)+C.
64.求(3x2y-2xy2)-(xy2-2x2y),其中x=-1,y=2.
65.已知|x+1|+(y-2)2=0,求代数式5(2x-y)-3(x-4y)的值.
66.当P=a2+2ab+b2,Q=a2-2ab-b2时,求P-[Q-2P-(P-Q)].
67.求2x2-{-3x+5+[4x2-(3x2-x-1)]}的值,其中x=-3.
68.当x=-2,y=-1,z=3时,求5xyz-{2x2y-[3xyz-(4xy2-x2y)]}的值.
69.已知A=x3-5x2,B=x2-6x+3,求A-3(-2B).
(五)综合练习
70.去括号:
{-[-(a+b)]}-{-[-(a-b)]}.
71.去括号:
-[-(-x)-y]-[+(-y)-(+x)].
72.已知A=x3+6x-9,B=-x3-2x2+4x-6,计算2A-3B,并把结果放在前面带“-”号的括号内.
73.计算下式,并把结果放在前面带“-”号的括号内:
(-7y2)+(-4y)-(-y2)-(+5y)+(-8y2)+(+3y).
74.不改变下式的值,将其中各括号前的符号都变成相反的符号:
(x3+3x2)-(3x2y-7xy)+(2y3-3y2).
75.把多项式4x2y-2xy2+4xy+6-x2y2+x3-y2的三次项放在前面带有“-”号的括号内,二次项放在前面带有“+”号的括号内,四次项和常数项放在前面带有“-”号的括号内.
76.把下列多项式的括号去掉,合并同类项,并将其各项放在前面带有“-”号的括号内,再求2x-2[3x-(5x2-2x+1)]-4x2的值,其中x=-1.
77.合并同类项:
7x-1.3z-4.7-3.2x-y+2.1z+5-0.1y.
78.合并同类项:
5m2n+5mn2-mn+3m2n-6mn2-8mn.
79.去括号,合并同类项:
(1)(m+1)-(-n+m);
(2)4m-[5m-(2m-1)].
80.化简:
2x2-{-3x-[4x2-(3x2-x)+(x-x2)]}.
81.化简:
-(7x-y-2z)-{[4x-(x-y-z)-3x+z]-x}.
82.计算:
(+3a)+(-5a)+(-7a)+(-31a)-(+4a)-(-8a).
83.化简:
a3-(a2-a)+(a2-a+1)-(1-a4+a3).
84.将x2-8x+2x3-13x2-2x-2x3+3先合并同类项,再求值,其中x=-4.
85.在括号内填上适当的项:
[()-9y+()]+2y2+3y-4=11y2-()+13.
86.在括号内填上适当的项:
(-x+y+z)(x+y-z)=[y-()][y+()].
87.在括号内填上适当的项:
(3x2+xy-7y2)-()=y2-2xy-x2.
88.在括号内填上适当的项:
(1)x2-xy+y-1=x2-();
(2)[()+6x-7]-[4x2+()-()]=x2-2x+1.
89.计算4x2-3[x+4(1-x)-x2]-2(4x2-1)的值.
90.化简:
(-x+5+2x4-6x3)-(3x4+2x2-3x3-7).
91.已知A=11x3+8x2-6x+2,B=7x3-x2+x+3,求2(3A-2B).
92.已知A=x3-5x2,B=x3-11x+6,C=4x-3,求
(1)A-B-C;
(2)(A-B-C)-(A-B+C).
93.已知A=3x2-4x3,B=x3-5x2+2,计算
(1)A+B;
(2)B-A.
94.已知x<-4,化简|-x|+|x+4|-|x-4|.
95.求两代数式-1.56a+3.2a3-0.47,2.27a3-0.02a2+4.03a+0.53的差与6-0.15a+3.24a2+5.07a3的和.
96.已知(x-3)2+|y+1|+z2=0,求x2-2xy-5x2+12xz+3xy-z2-8xz-2x2的值.
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