初二上化简求值题100道!急急急急

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匿名用户
2013-11-06
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1、已知A,B是方程x^2+2x-5=0的两个实数根,
求(A^2+2AB+2A)(B^2+2AB+2B)的值.
由A,B是方程x^2+2x-5=0的两个实数根得:
AB=-5,A+B=-2
A^2+2AB+2A)(B^2+2AB+2B)
=AB(A+2B+2)(B+2A+2)
=-5(-2+B+2)(-2+A+2)
=-5AB
=25

2、1/2(x+y+z)方+1/2(x-y-z)(x-y+z)-z(x+y),其中x-y=6,xy=21.要详细步骤
化简得:
1/2(x+y+z)方+1/2(x-y-z)(x-y+z)-z(x+y)=
1/2[(x+y)方+2z(x+y)+z方]+1/2[(x-y)方-z方]-z(x+y)=
1/2(x+y)方+1/2(x-y)方=x方+y方
由x-y=6,xy=21得,x方+y方=(x-y)方+2xy=78

3、a^2-ab+2b^2=3 求2ab-2a^2-4b^2-7的值
2ab-2a^2-4b^2-7
=2(ab-a^2-2b^2)-7
=-2(a^2-ab+2b^2)-7
=(-2)*3-7
=-6-7=-13

4、若A=2x^2+3xy-2x-3,B=-x^2+xy+2,且3A+6B的值与x无关,求y的值
解:
3A+6B=6x^2+9xy-6x-9-6x^2+6xy+12
=15xy-6x+3
=x(15y-6)+3

5、9x+6x^2 -3(x-2/3x^2).其中x=-2
9x+6x�0�5 -3(x-2/3x�0�5)
=9x+6x�0�5-3x+2x�0�5
=8x�0�5+6x
=8×(-2)�0�5+6×(-2)
=32-12
=20

6、1/4(-4x^2+2x-8)-(1/2x-1),其中x=1/2
1/4(-4x�0�5+2x-8)-(1/2x-1)
=-x�0�5+1/2x-2-1/2x+1
=-x�0�5-1
=-(1/2)�0�5-1
=-1/4-1
=-5/4

7、3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz,其中x=-2,y=-3,z=1,
:3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz
=3x'y-2x'y+2xyz-x'z+4x'z-xyz
=x'y-xyz+3x'z
=4*(-3)-2*3*1+3*4*1
=-12-6+12
=-6

8、(5a^2-3b^2)+(a^2+b^2)-(5a^2+3b^2),其中a=-1,b=1
=5a^2-3b^2+a^2+b^2-5a^2-3b^2
=a^2-5b^2
=(-1)^2-5*1^2
=1-5
=-4

9、2(a^2b+ab^2)-2(a^2 b-1)-2ab^2 -2其中a=-2,b=2
=2a^2b+2ab^2-2a^2b+2-2ab^2-2
=0

10、(X-2分之1Y-1)(X-2分之1Y+1)-(X-2分之1Y-1)的平方
其中X=1.7,Y=3.9(先化简再求值)
[(X-2分之1Y)-1][(X+2分之1Y)+1]-(X-2分之1Y-1)平方
=(X+2分之1Y)平方-1-(X-2分之1Y)平方+2(X-2分之1Y)-1
=(X+2分之1Y)平方-(X-2分之1Y)平方+2(X-2分之1Y)-2
=2XY+2X-Y-2
=3.9*2.4+1.4
=10.76

化间求值: 下面的你自己求吧```
1、-9(x-2)-y(x-5)
(1)化简整个式子。
(2)当x=5时,求y的解。
2、5(9+a)×b-5(5+b)×a
(1)化简整个式子。
(2)当a=5/7时,求式子的值。
3、62g+62(g+b)-b
(1)化简整个式子。
(2)当g=5/7时,求b的解。
4、3(x+y)-5(4+x)+2y
(1)化简整个式子。
5、(x+y)(x-y)
(1)化简整个式子。
6、2ab+a×a-b
(1)化简整个式子。
7、5.6x+4(x+y)-y
(1)化简整个式子。
8、6.4(x+2.9)-y+2(x-y)
(1)化简整个式子。
9、(2.5+x)(5.2+y)
(1)化简整个式子。
10、9.77x-(5-a)x+2a
(5a^2-3b^2)+(a^2+b^2)-(5a^2+3b^2),其中a=-1,b=1
=5a^2-3b^2+a^2+b^2-5a^2-3b^2
=a^2-5b^2
=(-1)^2-5*1^2
=1-5
=-4
2(a^2b+ab^2)-2(a^2 b-1)-2ab^2 -2其中a=-2,b=2
=2a^2b+2ab^2-2a^2b+2-2ab^2-2
=0
x+7-(-36+8^2)/2=[-(-8x)+7^4]/3*(8^2-6x)
(a-7)-(-98a)+7a=[(3.2*5a)2^5]/10
(89/2+5x)+35/6x=[3*(-9+5)+2^3]/5+7x
[3X+(-189+5^2)/3]/8=521/2
4y+[119*(-5^3y+8/7)-8/3]=22/11
(3X*189)+{5*6+[-5/8*(-65*8^3)]+9/2}
7(2x-1)-3(4x-1)=4(3x+2)-1
(5y+1)+ (1-y)= (9y+1)+ (1-3y)
[-6(-7^4*8)-4]=x+2
20%+(1-20%)(320-x)=320×40%
2(x-2)+2=x+1
2(x-2)-3(4x-1)=9(1-x)
11x+64-2x=100-9x
15-(8-5x)=7x+(4-3x)
3(x-7)-2[9-4(2-x)]=22
3/2[2/3(1/4x-1)-2]-x=2
2x+7^2=157
9x+6x�0�5 -3(x-2/3x�0�5)
=9x+6x�0�5-3x+2x�0�5
=8x�0�5+6x
=8×(-2)�0�5+6×(-2)
=32-12
=20

1/4(-4x�0�5+2x-8)-(1/2x-1)
=-x�0�5+1/2x-2-1/2x+1
=-x�0�5-1
=-(1/2)�0�5-1
=-1/4-1
=-5/4
3.3ab-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,计算A+B=______.

22.已知A=x3-2x2+x-4,B=2x3-5x+3,计算A-B=______.

23.若a=-0.2,b=0.5,代数式-(|a2b|-|ab2|)的值为______.

25.一个多项式减去3m4-m3-2m+5得-2m4-3m3-2m2-1,那么这个多项式等于______.

26.-(2x2-y2)-[2y2-(x2+2xy)]=______.

27.若-3a3b2与5ax-1by+2是同类项,则x=______,y=______.

28.(-y+6+3y4-y3)-(2y2-3y3+y4-7)=______.

29.化简代数式4x2-[7x2-5x-3(1-2x+x2)]的结果是______.

30.2a-b2+c-d3=2a+( )-d3=2a-d3-( )=c-( ).

31.3a-(2a-3b)+3(a-2b)-b=______.

32.化简代数式x-[y-2x-(x+y)]等于______.

33.[5a2+( )a-7]+[( )a2-4a+( )]=a2+2a+1.

34.3x-[y-(2x+y)]=______.

35.化简|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,化简|x+y|-|5-x-y|=______.

38.4a2n-an-(3an-2a2n)=______.

39.若一个多项式加上-3x2y+2x2-3xy-4得

2x2y+3xy2-x2+2xy,

则这个多项式为______.

40.-5xm-xm-(-7xm)+(-3xm)=______.

41.当a=-1,b=-2时,

[a-(b-c)]-[-b-(-c-a)]=______.

43.当a=-1,b=1,c=-1时,

-[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.当2y-x=5时,5(x-2y)2-3(-x+2y)-100=______.

(二)选择

[ ]

A.2;

B.-2;

C.-10;

D.-6.

52.下列各式中计算结果为-7x-5x2+6x3的是 [ ]

A.3x-(5x2+6x3-10x);

B.3x-(5x2+6x3+10x);

C.3x-(5x2-6x3+10x);

D.3x-(5x2-6x3-10x).

53.把(-x-y)+3(x+y)-5(x+y)合并同类项得 [ ]

A.(x-y)-2(x+y);

B.-3(x+y);

C.(-x-y)-2(x+y);

D.3(x+y).

54.2a-[3b-5a-(2a-7b)]等于 [ ]

A.-7a+10b;

B.5a+4b;

C.-a-4b;

D.9a-10b.

55.减去-3m等于5m2-3m-5的代数式是 [ ]

A.5(m2-1);

B.5m2-6m-5;

C.5(m2+1);

D.-(5m2+6m-5).

56.将多项式2ab-9a2-5ab-4a2中的同类项分别结合在一起,应为 [ ]

A.(9a2-4a2)+(-2ab-5ab);

B.(9a2+4a2)-(2ab-5ab);

C.(9a2-4a2)-(2ab+5ab);

D.(9a2-4a2)+(2ab-5ab).

57.当a=2,b=1时,-a2b+3ba2-(-2a2b)等于 [ ]

A.20;

B.24;

C.0;

D.16.

中,正确的选择是 [ ]

A.没有同类项;

B.(2)与(4)是同类项;

C.(2)与(5)是同类项;

D.(2)与(4)不是同类项.

59.若A和B均为五次多项式,则A-B一定是 [ ]

A.十次多项式;

B.零次多项式;

C.次数不高于五次的多项式;

D.次数低于五次的多项式.

60.-{[-(x+y)]}+{-[(x+y)]}等于 [ ]

A.0;

B.-2y;

C.x+y;

D.-2x-2y.

61.若A=3x2-5x+2,B=3x2-5x+6,则A与B的大小是

[ ]

A.A>B;

B.A=B;

C.A<B;

D.无法确定.

62.当m=-1时,-2m2-[-4m2+(-m2)]等于 [ ]

A.-7;

B.3;

C.1;

D.2.

63.当m=2,n=1时,多项式-m-[-(2m-3n)]+[-(-3m)-4n]等于 [ ]

A.1;

B.9;

C.3;

D.5.

[ ]

65.-5an-an-(-7an)+(-3an)等于 [ ]

A.-16an;

B.-16;

C.-2an;

D.-2.

66.(5a-3b)-3(a2-2b)等于 [ ]

A.3a2+5a+3b;

B.2a2+3b;

C.2a3-b2;

D.-3a2+5a-5b.

67.x3-5x2-4x+9等于 [ ]

A.(x3-5x2)-(-4x+9);

B.x3-5x2-(4x+9);

C.-(-x3+5x2)-(4x-9);

D.x3+9-(5x2-4x).

[ ]

69.4x2y-5xy2的结果应为 [ ]

A.-x2y;

B.-1;

C.-x2y2;

D.以上答案都不对.

(三)化简

70.(4x2-8x+5)-(x3+3x2-6x+2).

72.(0.3x3-x2y+xy2-y3)-(-0.5x3-x2y+0.3xy2).

73.-{2a2b-[3abc-(4ab2-a2b)]}.

74.(5a2b+3a2b2-ab2)-(-2ab2+3a2b2+a2b).

75.(x2-2y2-z2)-(-y2+3x2-z2)+(5x2-y2+2z2).

76.(3a6-a4+2a5-4a3-1)-(2-a+a3-a5-a4).

77.(4a-2b-c)-5a-[8b-2c-(a+b)].

78.(2m-3n)-(3m-2n)+(5n+m).

79.(3a2-4ab-5b2)-(2b2-5a2+2ab)-(-6ab).

80.xy-(2xy-3z)+(3xy-4z).

81.(-3x3+2x2-5x+1)-(5-6x-x2+x3).

83.3x-(2x-4y-6x)+3(-2z+2y).

84.(-x2+4+3x4-x3)-(x2+2x-x4-5).

85.若A=5a2-2ab+3b2,B=-2b2+3ab-a2,计算A+B.

86.已知A=3a2-5a-12,B=2a2+3a-4,求2(A-B).

87.2m-{-3n+[-4m-(3m-n)]}.

88.5m2n+(-2m2n)+2mn2-(+m2n).

89.4(x-y+z)-2(x+y-z)-3(-x-y-z).

90.2(x2-2xy+y2-3)+(-x2+y2)-(x2+2xy+y2).

92.2(a2-ab-b2)-3(4a-2b)+2(7a2-4ab+b2).

94.4x-2(x-3)-3[x-3(4-2x)+8].

(四)将下列各式先化简,再求值

97.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.

98.已知A=a2+2b2-3c2,B=-b2-2c2+3a2,C=c2+2a2-3b2,求(A-B)+C.

99.求(3x2y-2xy2)-(xy2-2x2y),其中x=-1,y=2.

101.已知|x+1|+(y-2)2=0,求代数式5(2x-y)-3(x-4y)的值.

106.当P=a2+2ab+b2,Q=a2-2ab-b2时,求P-[Q-2P-(P-Q)].

107.求2x2-{-3x+5+[4x2-(3x2-x-1)]}的值,其中x=-3.

110.当x=-2,y=-1,z=3时,求5xyz-{2x2y-[3xyz-(4xy2-x2y)]}的值.

113.已知A=x3-5x2,B=x2-6x+3,求A-3(-2B).

(五)综合练习

115.去括号:{-[-(a+b)]}-{-[-(a-b)]}.

116.去括号:-[-(-x)-y]-[+(-y)-(+x)].

117.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.

118.计算下式,并把结果放在前面带“-”号的括号内:

(-7y2)+(-4y)-(-y2)-(+5y)+(-8y2)+(+3y).

119.去括号、合并同类项,将结果按x的升幂排列,并把后三项放在带有“-”号的括号内:

120.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).

121.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.

122.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.

123.合并同类项:

7x-1.3z-4.7-3.2x-y+2.1z+5-0.1y.

124.合并同类项:5m2n+5mn2-mn+3m2n-6mn2-8mn.

126.去括号,合并同类项:

(1)(m+1)-(-n+m);

(2)4m-[5m-(2m-1)].

127.化简:2x2-{-3x-[4x2-(3x2-x)+(x-x2)]}.

128.化简:-(7x-y-2z)-{[4x-(x-y-z)-3x+z]-x}.

129.计算:(+3a)+(-5a)+(-7a)+(-31a)-(+4a)-(-8a).

130.化简:a3-(a2-a)+(a2-a+1)-(1-a4+a3).

131.将x2-8x+2x3-13x2-2x-2x3+3先合并同类项,再求值,其中x=-4.

132.在括号内填上适当的项:[( )-9y+( )]+2y2+3y-4=11y2-( )+13.

133.在括号内填上适当的项:

(-x+y+z)(x+y-z)=[y-( )][y+( )].

134.在括号内填上适当的项:

(3x2+xy-7y2)-( )=y2-2xy-x2.

135.在括号内填上适当的项:

(1)x2-xy+y-1=x2-( );

(2)[( )+6x-7]-[4x2+( )-( )]=x2-2x+1.

136.计算4x2-3[x+4(1-x)-x2]-2(4x2-1)的值.

137.化简:

138.用竖式计算

(-x+5+2x4-6x3)-(3x4+2x2-3x3-7).

139.已知A=11x3+8x2-6x+2,B=7x3-x2+x+3,求2(3A-2B).

140.已知A=x3-5x2,B=x3-11x+6,C=4x-3,求

(1)A-B-C;

(2)(A-B-C)-(A-B+C).

141.已知A=3x2-4x3,B=x3-5x2+2,计算

(1)A+B;

(2)B-A.

142.已知x<-4,化简|-x|+|x+4|-|x-4|.

146.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.

-0.3,y=-0.2.

150.已知(x-3)2+|y+1|+z2=0,求x2-2xy-5x2+12xz+3xy-z2-8xz-2x2的值.
匿名用户
2013-11-06
展开全部
这个自己弄吧,兄弟,这里就算有也都是在网上随便复制的骗分的!~
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