1:(1)解:原式=(1-3)x²y+1=-2x²y+1
(2)解:原式=7x-3z-8y+5z=7x-8y+(-3+5)=7x-8y+2z
(3)解:原式=x+[3x+1-4+x]=x+3x+1-4+x=(1+3+1)x-3=5x-3
(4)解:原式=x²-y²-6x²+9y²=(1-6)x²+(-1+9)y²=-5x²+8y²
2:(1)解:原式=3x-3-x+5=(3-1)x+2=2x+2 当x=2时,原式=2*2+2=4+2=6
(2)解:原式=2x²-y²+2y²-x²-x²+2y²=(2-1-1)x²+(-1+2+2)y²=3y² 当x=15/101,y=1时,原式=3*1=3
3:A-2B=(5x²y+4xy)-2(-2xy+x²y)=5x²y+4xy+4xy-2x²y=(5-2)x²y+(4+4)xy=3x²y+8xy
4:(10b+a)-(10a+b)=10b+a-10a-b=(10-1)b+(1-10)a=9b-9a
5:棉花用地6x+y亩 当x=120,y=4时,原式=6*120+4=720(亩)
6:2x²-3xy+y²-2xy-2x²+5xy-2y+1=(2-2)x²+(-3-2+5)xy+(1-2)y+1=-y+1
答:因为结果中不含x项,所以原式的结果与x无关
7:因为x的相反数是-5所以x=5 因为5|m|=0所以m=0因为2a²b y次方与7b²a²是同类项所以y=2
2x²-6y²+m(xy-9y²)-(3x²-3xy+7y²)=2*5²-6*2²+0(5*2-92²)-(3*2²-3*5*2+7*2²)=50-24+0-(12-30+28)=50-24+0-12+30-28=16
写了半小时 你可一定要选我哇要不我白写了 1、①原式=1-2x²y
②原式=7x-3z-8y+5z=7x-8y+2z
③原式=x+3x+1-4+x=5x-3
④原式=x²-y²-6x²+9y²=8y²-5x²
2、①原式=3x-3-x+5=2x+2=6
②原式=2x²-y²+2y²-x²-x²+2y²=3y²=3
3、A-2B=5x²y+4xy-2(-2xy+x²y)=5x²y+4xy+4xy-2x²y=3x²y+8xy
4、 10a+b-10b-a=9(a-b)
5、蔬菜:x,粮食:6x+y
棉花=1000-x-6x-y=1000-7x-y=156
6、原式=y²-2y+1=(y-1)²=4
x的值在运算中消去了,没参加计算,所以结果是一样的
7、①x的相反数是-5;所以x=5
②5|m|=0;所以m=0
③-2a²b^y与7b²a²是同类项,所以y=2
2x²-6y²+m(xy-9y²)-(3x²-3xy+7y²)=-x²-13y²+3xy=-5²-13*2²=3*5*2=-47
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=______.
.(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).
93.2x2-{-3x-[4x2-(3x2-x)+(x-x2)]}.
94:-(7x-y-2z)-{[4x-(x-y-z)-3x+z]-x}.
95:(+3a)+(-5a)+(-7a)+(-31a)-(+4a)-(-8a).
96:a3-(a2-a)+(a2-a+1)-(1-a4+a3).
97.4x-2(x-3)-3[x-3(4-2x)+8].
上面的题加参考资料上的,我想就够了哦~~
1,(2a+3b)²=4a²+12ab+9b²,
2,(a+2b)(3a+b)=3a²+7ab+2b²,
3,(a-2b)(3a+b)=3a²-5ab-2b²,
4,(a+2b)(3a-b)=3a²+5ab-2b²,
5,(a-2b)(3a-b)=3a²-7ab+2b²,
6,(a+2b)(3a+b+2c)=3a²+7ab+2b²+2ac+4bc,
7,(a+2b)(3a+b-2c)=3a²+7ab+2b²-2ac-4bc,
8,(a+2b+c)(3a+b+2c)=3a²+2b²+2c ²+7ab+5ac+5bc,
9,(a+2b-c)(3a+b+2c)=3a²+2b²-2c ²+7ab-ac+3bc,
10,(a+2b-c)(3a+b-2c)=3a²+2b²+2c ²+7ab-5ac-5bc,
11,(x+2y)3=x3+6x²y+12xy²+8y3,
12,(x-2y)3=x3-6x²y+12xy²-8y3,
13(2x+y+3z)²=4x²+y²+9z²+4xy+6yz+12zx
15,(2x-y+3z)²=4x²+y²+9z²-4xy-6yz+12zx
16,(2x+y-3z)²=4x²+y²+9z²+4xy-6yz-12zx,
18,(2x+y)(4x²-2xy+y²)=-8x3+y3,
19,(2x-y)(4x²+2xy+y²)=-8x3-y3,
20,2ax(x3y+3x²y²+xy²+x+a+5)=2ax4y+6ax3y3+2x²y²+2ax²+2a²x+10ax,
1、(3ab-2a)÷a
2、(x^3-2x^y)÷(-x^2)
3、-21a^2b^3÷7a^2b
4、(6a^3b-9a^c)÷3a^2
5、(5ax^2+15x)÷5x
6、(a+2b)(a-2b)
7、(3a+b)^2
8、(1/2 a-1/3 b)^2
9、(x+5y)(x-7y)
10、(2a+3b)(2a+3b)
11、(x+5)(x-7)
12、5x^3×8x^2
13、-3x×(2x^2-x+4)
14、11x^12×(-12x^11)
15、(x+5)(x+6)
16、(2x+1)(2x+3)
17、3x^3y×(2x^2y-3xy)
18、2x×(3x^2-xy+y^2)
19、(a^3)^3÷(a^4)^2
20、(x^2y)^5÷(x^2y)^3
21、(y^3)^3÷y^3÷(-y^2)^2
22、(-2mn^3)^3
23、(2x-1)(3x+2)
24、(2/3 x+3/4y)^2
25、2001^2-2002×2002
26、(2x+5)^2-(2x-5)^2
27、-12m^3n^3÷4m^2n^3
28、2x^2y^2-4y^3z
29、1-4x^2
30、x^3-25x
31、x^3+4x^2+4x
32、(x+2)(x+6)
33、2a×3a^2
34、(-2mn^2)^3
35、(-m+n)(m-n)
36、27x^8÷3x^4
37、(-2x^2)×(-y)+3xy×(1-1/3 x)
38、am-an+ap
39、25x^2+20xy+4y^2
40、(-4m^4+20m^3n-m^2n^2)÷(-4m^2)
41、(12p^3q^4+20p^3q^2r-6p^4q^3)÷(-2pq)^2
42、[4y(2x-y)-2x(2x-y)]÷(2x-y)
43、(x^2y^3-1/2 x^3y^2+2x^2y^2)÷1/2 xy^2
44、(4a^3b^3-6a^2b^3c-2ab^5)÷(-2ab^2)
45、(ax+bx)÷x
46、(ma+mb+mc)÷m
47、(9x^4-15x^2+6x)÷3x
48、(28a^3b^2c+a^2b^3-14a^2b^2)÷(-7a^2b)
49、(6xy^2)^2÷3xy
50、24a^3b^2÷3ab^2 (3x+5y)(3x-2y) (x+11)(x-20) (-3x)(2xy-6) x(x2-x)+2x2(x-1)
(m-30)(m+30) (2x-9)(2x+9) (2x-3t)(2x+3t) (3x-7)(3x+7)
(-2m+n)(n+2m) (-5p-3)(5p-3) (x+2)(x+3) (x2-y)(x2+y)
(-2a3)·(2a2b-4ab2) (2x-y)(2x+y) (-3ab)2·(-2ab2) (x-1)(x+1)-x2
(x-2)(x+3) (x+2)(x-3) (x-2)(x-3) (x+2y)(x-2y) (3a-4b)(2a-5b) (5x-4y)(2x-3y) (3x+4y)(3x-4y) (2a-3b)(3a+2b)
(2m+5m)(6n-3m) (3x-y)(3x-y) (6x-y)(6x+y) (2x+y)(-2x-y) (x-5)(x+5) (3y-10)(3y+10) (8-5b)( +5b) (a-5b)(+5b)
(a-bc)(a+bc) (a+2b)(2b-a) (3x-y)(y+3x) 4x2-(2x-9)(2x+9)
(-7m+1)(-7m-1) (-x-5)(-x+5) (x2-2)(x2+2) (-2x-11y)(2x-11y)
(ab-3)(ab+3) (4y-3x)(3x+4y) (x+1)(x-1)-x² (4+2x)(2-x)
(3y-1)(3y+1)-(2y+2)(2y-2) (-3m2+1)(-3m2-1) (5x-2y)2+20xy
(a-2b)(a+2b)-(a-2b)2 2x2y-3y2 a(x+y)-2(x+y) (x+y)2-3(y+x) x(x-y)-a(y-x) (a+b)-a(a+b) (x-5)(x+5) (a2-5b)( +5b) x(a-b)-5(a-b) (x-y)2-(x-y) 3(2x+y)2+2(2x+y) (3y-10)(3y+10)
(xy3)(xy+3) 16m2+25-40m 18x2y-24xy2 -3a3b2+12b3a2 (2m-3n)(2n-5m) 3a2-6ab+3ab2 2x2y-3b2 没答案sorry
整式加减计算题
例题
例1、合并同类项
(1)(3x-5y)-(6x+7y)+(9x-2y)
(2)2a-[3b-5a-(3a-5b)]
(3)(6m2n-5mn2)-6(m2n-mn2)
解:(1)(3x-5y)-(6x+7y)+(9x-2y)
=3x-5y-6x-7y+9x-2y (正确去掉括号)
=(3-6+9)x+(-5-7-2)y (合并同类项)
=6x-14y
(2)2a-[3b-5a-(3a-5b)] (应按小括号,中括号,大括号的顺序逐层去括号)
=2a-[3b-5a-3a+5b] (先去小括号)
=2a-[-8a+8b] (及时合并同类项)
=2a+8a-8b (去中括号)
=10a-8b
(3)(6m2n-5mn2)-6(m2n-mn2) (注意第二个括号前有因数6)
=6m2n-5mn2-2m2n+3mn2 (去括号与分配律同时进行)
=(6-2)m2n+(-5+3)mn2 (合并同类项)
=4m2n-2mn2
例2.已知:A=3x2-4xy+2y2,B=x2+2xy-5y2
求:(1)A+B (2)A-B (3)若2A-B+C=0,求C。
解:(1)A+B=(3x2-4xy+2y2)+(x2+2xy-5y2)
=3x2-4xy+2y2+x2+2xy-5y2(去括号)
=(3+1)x2+(-4+2)xy+(2-5)y2(合并同类项)
=4x2-2xy-3y2(按x的降幂排列)
(2)A-B=(3x2-4xy+2y2)-(x2+2xy-5y2)
=3x2-4xy+2y2-x2-2xy+5y2 (去括号)
=(3-1)x2+(-4-2)xy+(2+5)y2 (合并同类项)
=2x2-6xy+7y2 (按x的降幂排列)
(3)∵2A-B+C=0
∴C=-2A+B
=-2(3x2-4xy+2y2)+(x2+2xy-5y2)
=-6x2+8xy-4y2+x2+2xy-5y2 (去括号,注意使用分配律)
=(-6+1)x2+(8+2)xy+(-4-5)y2 (合并同类项)
=-5x2+10xy-9y2 (按x的降幂排列)
例3.计算:
(1)m2+(-mn)-n2+(-m2)-(-0.5n2)
(2)2(4an+2-an)-3an+(an+1-2an+1)-(8an+2+3an)
(3)化简:(x-y)2-(x-y)2-[(x-y)2-(x-y)2]
解:(1)m2+(-mn)-n2+(-m2)-(-0.5n2)
=m2-mn-n2-m2+n2 (去括号)
=(-)m2-mn+(-+)n2 (合并同类项)
=-m2-mn-n2 (按m的降幂排列)
(2)2(4an+2-an)-3an+(an+1-2an+1)-(8an+2+3an)
=8an+2-2an-3an-an+1-8an+2-3an (去括号)
=0+(-2-3-3)an-an+1 (合并同类项)
=-an+1-8an
(3)(x-y)2-(x-y)2-[(x-y)2-(x-y)2] [把(x-y)2看作一个整体]
=(x-y)2-(x-y)2-(x-y)2+(x-y)2 (去掉中括号)
=(1--+)(x-y)2 (“合并同类项”)
=(x-y)2
例4求3x2-2{x-5[x-3(x-2x2)-3(x2-2x)]-(x-1)}的值,其中x=2。
分析:由于已知所给的式子比较复杂,一般情况都应先化简整式,然后再代入所给数值x=-2,去括号时要注意符号,并且及时合并同类项,使运算简便。
解:原式=3x2-2{x-5[x-3x+6x2-3x2+6x]-x+1} (去小括号)
=3x2-2{x-5[3x2+4x]-x+1} (及时合并同类项)
=3x2-2{x-15x2-20x-x+1} (去中括号)
=3x2-2{-15x2-20x+1} (化简大括号里的式子)
=3x2+30x2+40x-2 (去掉大括号)
=33x2+40x-2
当x=-2时,原式=33×(-2)2+40×(-2)-2=132-80-2=50
例5.若16x3m-1y5和-x5y2n+1是同类项,求3m+2n的值。
解:∵16x3m-1y5和-x5y2n+1是同类项
∴对应x,y的次数应分别相等
∴3m-1=5且2n+1=5
∴m=2且n=2
∴3m+2n=6+4=10
本题考察我们对同类项的概念的理解。
例6.已知x+y=6,xy=-4,求: (5x-4y-3xy)-(8x-y+2xy)的值。
解:(5x-4y-3xy)-(8x-y+2xy)
=5x-4y-3xy-8x+y-2xy
=-3x-3y-5xy
=-3(x+y)-5xy
∵x+y=6,xy=-4
∴原式=-3×6-5×(-4)=-18+20=2
说明:本题化简后,发现结果可以写成-3(x+y)-5xy的形式,因而可以把x+y,xy的值代入原式即可求得最后结果,而没有必要求出x,y的值,这种思考问题的思想方法叫做整体代换,希望同学们在学习过程中,注意使用。
练习
(一)计算:
(1)a-(a-3b+4c)+3(-c+2b)
(2)(3x2-2xy+7)-(-4x2+5xy+6)
(3)2x2-{-3x+6+[4x2-(2x2-3x+2)]}
(二)化简
(1)a>0,b<0,|6-5b|-|3a-2b|-|6b-1|
(2)1 (三)当a=1,b=-3,c=1时,求代数式a2b-[a2b-(5abc-a2c)]-5abc的值。 (四)当代数式-(3x+6)2+2取得最大值时,求代数式5x-[-x2-(x+2)]的值。 (五)x2-3xy=-5,xy+y2=3,求x2-2xy+y2的值。 练习参考答案: (一)计算: (1)-a+9b-7c (2)7x2-7xy+1 (3)-4 (二)化简 (1)∵a>0, b<0 ∴|6-5b|-|3a-2b|-|6b-1| =6-5b-(3a-2b)-(1-6b) =6-5b-3a+2b-1+6b=-3a+3b+5 (2)∵1 ∴|1-a|+|3-a|+|a-5|=a-1+3-a+5-a=-a+7 (三)原式=-a2b-a2c= 2 (四)根据题意,x=-2,当x=-2时,原式=- (五)-2(用整体代换) 有一条铁丝长a米,第一次用去了一半少1米,第二次用去了剩余的一半多1米,这条铁丝还剩余多少米? 答案:列式:a-1/2(a-1)={1/2(a-1)}1/2+a 得出结果:a=3/2 1:(1)解:原式=(1-3)x²y+1=-2x²y+1 (2)解:原式=7x-3z-8y+5z=7x-8y+(-3+5)=7x-8y+2z (3)解:原式=x+[3x+1-4+x]=x+3x+1-4+x=(1+3+1)x-3=5x-3 (4)解:原式=x²-y²-6x²+9y²=(1-6)x²+(-1+9)y²=-5x²+8y² 2:(1)解:原式=3x-3-x+5=(3-1)x+2=2x+2 当x=2时,原式=2*2+2=4+2=6 (2)解:原式=2x²-y²+2y²-x²-x²+2y²=(2-1-1)x²+(-1+2+2)y²=3y² 当x=15/101,y=1时,原式=3*1=3 3:A-2B=(5x²y+4xy)-2(-2xy+x²y)=5x²y+4xy+4xy-2x²y=(5-2)x²y+(4+4)xy=3x²y+8xy 4:(10b+a)-(10a+b)=10b+a-10a-b=(10-1)b+(1-10)a=9b-9a 5:棉花用地6x+y亩 当x=120,y=4时,原式=6*120+4=720(亩) 6:2x²-3xy+y²-2xy-2x²+5xy-2y+1=(2-2)x²+(-3-2+5)xy+(1-2)y+1=-y+1 答:因为结果中不含x项,所以原式的结果与x无关 7:因为x的相反数是-5所以x=5 因为5|m|=0所以m=0因为2a²b y次方与7b²a²是同类项所以y=2 2x²-6y²+m(xy-9y²)-(3x²-3xy+7y²)=2*5²-6*2²+0(5*2-92²)-(3*2²-3*5*2+7*2²)=50-24+0-(12-30+28)=50-24+0-12+30-28=16 写了半小时 你可一定要选我哇要不我白写了 1、①原式=1-2x²y ②原式=7x-3z-8y+5z=7x-8y+2z ③原式=x+3x+1-4+x=5x-3 ④原式=x²-y²-6x²+9y²=8y²-5x² 2、①原式=3x-3-x+5=2x+2=6 ②原式=2x²-y²+2y²-x²-x²+2y²=3y²=3 3、A-2B=5x²y+4xy-2(-2xy+x²y)=5x²y+4xy+4xy-2x²y=3x²y+8xy 4、 10a+b-10b-a=9(a-b) 5、蔬菜:x,粮食:6x+y 棉花=1000-x-6x-y=1000-7x-y=156 6、原式=y²-2y+1=(y-1)²=4 x的值在运算中消去了,没参加计算,所以结果是一样的 7、①x的相反数是-5;所以x=5 ②5|m|=0;所以m=0 ③-2a²b^y与7b²a²是同类项,所以y=2 2x²-6y²+m(xy-9y²)-(3x²-3xy+7y²)=-x²-13y²+3xy=-5²-13*2²=3*5*2=-47 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=______. .(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). 93.2x2-{-3x-[4x2-(3x2-x)+(x-x2)]}. 94:-(7x-y-2z)-{[4x-(x-y-z)-3x+z]-x}. 95:(+3a)+(-5a)+(-7a)+(-31a)-(+4a)-(-8a). 96:a3-(a2-a)+(a2-a+1)-(1-a4+a3). 97.4x-2(x-3)-3[x-3(4-2x)+8]. 上面的题加参考资料上的,我想就够了哦~~ 1,(2a+3b)²=4a²+12ab+9b², 2,(a+2b)(3a+b)=3a²+7ab+2b², 3,(a-2b)(3a+b)=3a²-5ab-2b², 4,(a+2b)(3a-b)=3a²+5ab-2b², 5,(a-2b)(3a-b)=3a²-7ab+2b², 6,(a+2b)(3a+b+2c)=3a²+7ab+2b²+2ac+4bc, 7,(a+2b)(3a+b-2c)=3a²+7ab+2b²-2ac-4bc, 8,(a+2b+c)(3a+b+2c)=3a²+2b²+2c ²+7ab+5ac+5bc, 9,(a+2b-c)(3a+b+2c)=3a²+2b²-2c ²+7ab-ac+3bc, 10,(a+2b-c)(3a+b-2c)=3a²+2b²+2c ²+7ab-5ac-5bc, 11,(x+2y)3=x3+6x²y+12xy²+8y3, 12,(x-2y)3=x3-6x²y+12xy²-8y3, 13(2x+y+3z)²=4x²+y²+9z²+4xy+6yz+12zx 15,(2x-y+3z)²=4x²+y²+9z²-4xy-6yz+12zx 16,(2x+y-3z)²=4x²+y²+9z²+4xy-6yz-12zx, 18,(2x+y)(4x²-2xy+y²)=-8x3+y3, 19,(2x-y)(4x²+2xy+y²)=-8x3-y3, 20,2ax(x3y+3x²y²+xy²+x+a+5)=2ax4y+6ax3y3+2x²y²+2ax²+2a²x+10ax, 1、(3ab-2a)÷a 2、(x^3-2x^y)÷(-x^2) 3、-21a^2b^3÷7a^2b 4、(6a^3b-9a^c)÷3a^2 5、(5ax^2+15x)÷5x 6、(a+2b)(a-2b) 7、(3a+b)^2 8、(1/2 a-1/3 b)^2 9、(x+5y)(x-7y) 10、(2a+3b)(2a+3b) 11、(x+5)(x-7) 12、5x^3×8x^2 13、-3x×(2x^2-x+4) 14、11x^12×(-12x^11) 15、(x+5)(x+6) 16、(2x+1)(2x+3) 17、3x^3y×(2x^2y-3xy) 18、2x×(3x^2-xy+y^2) 19、(a^3)^3÷(a^4)^2 20、(x^2y)^5÷(x^2y)^3 21、(y^3)^3÷y^3÷(-y^2)^2 22、(-2mn^3)^3 23、(2x-1)(3x+2) 24、(2/3 x+3/4y)^2 25、2001^2-2002×2002 26、(2x+5)^2-(2x-5)^2 27、-12m^3n^3÷4m^2n^3 28、2x^2y^2-4y^3z 29、1-4x^2 30、x^3-25x 31、x^3+4x^2+4x 32、(x+2)(x+6) 33、2a×3a^2 34、(-2mn^2)^3 35、(-m+n)(m-n) 36、27x^8÷3x^4 37、(-2x^2)×(-y)+3xy×(1-1/3 x) 38、am-an+ap 39、25x^2+20xy+4y^2 40、(-4m^4+20m^3n-m^2n^2)÷(-4m^2) 41、(12p^3q^4+20p^3q^2r-6p^4q^3)÷(-2pq)^2 42、[4y(2x-y)-2x(2x-y)]÷(2x-y) 43、(x^2y^3-1/2 x^3y^2+2x^2y^2)÷1/2 xy^2 44、(4a^3b^3-6a^2b^3c-2ab^5)÷(-2ab^2) 45、(ax+bx)÷x 46、(ma+mb+mc)÷m 47、(9x^4-15x^2+6x)÷3x 48、(28a^3b^2c+a^2b^3-14a^2b^2)÷(-7a^2b) 49、(6xy^2)^2÷3xy 50、24a^3b^2÷3ab^2 (3x+5y)(3x-2y) (x+11)(x-20) (-3x)(2xy-6) x(x2-x)+2x2(x-1) (m-30)(m+30) (2x-9)(2x+9) (2x-3t)(2x+3t) (3x-7)(3x+7) (-2m+n)(n+2m) (-5p-3)(5p-3) (x+2)(x+3) (x2-y)(x2+y) (-2a3)·(2a2b-4ab2) (2x-y)(2x+y) (-3ab)2·(-2ab2) (x-1)(x+1)-x2 (x-2)(x+3) (x+2)(x-3) (x-2)(x-3) (x+2y)(x-2y) (3a-4b)(2a-5b) (5x-4y)(2x-3y) (3x+4y)(3x-4y) (2a-3b)(3a+2b) (2m+5m)(6n-3m) (3x-y)(3x-y) (6x-y)(6x+y) (2x+y)(-2x-y) (x-5)(x+5) (3y-10)(3y+10) (8-5b)( +5b) (a-5b)(+5b) (a-bc)(a+bc) (a+2b)(2b-a) (3x-y)(y+3x) 4x2-(2x-9)(2x+9) (-7m+1)(-7m-1) (-x-5)(-x+5) (x2-2)(x2+2) (-2x-11y)(2x-11y) (ab-3)(ab+3) (4y-3x)(3x+4y) (x+1)(x-1)-x² (4+2x)(2-x) (3y-1)(3y+1)-(2y+2)(2y-2) (-3m2+1)(-3m2-1) (5x-2y)2+20xy (a-2b)(a+2b)-(a-2b)2 2x2y-3y2 a(x+y)-2(x+y) (x+y)2-3(y+x) x(x-y)-a(y-x) (a+b)-a(a+b) (x-5)(x+5) (a2-5b)( +5b) x(a-b)-5(a-b) (x-y)2-(x-y) 3(2x+y)2+2(2x+y) (3y-10)(3y+10) (xy3)(xy+3) 16m2+25-40m 18x2y-24xy2 -3a3b2+12b3a2 (2m-3n)(2n-5m) 3a2-6ab+3ab2 2x2y-3b2 没答案sorry 整式加减计算题 例题 例1、合并同类项 (1)(3x-5y)-(6x+7y)+(9x-2y) (2)2a-[3b-5a-(3a-5b)] (3)(6m2n-5mn2)-6(m2n-mn2) 解:(1)(3x-5y)-(6x+7y)+(9x-2y) =3x-5y-6x-7y+9x-2y (正确去掉括号) =(3-6+9)x+(-5-7-2)y (合并同类项) =6x-14y (2)2a-[3b-5a-(3a-5b)] (应按小括号,中括号,大括号的顺序逐层去括号) =2a-[3b-5a-3a+5b] (先去小括号) =2a-[-8a+8b] (及时合并同类项) =2a+8a-8b (去中括号) =10a-8b (3)(6m2n-5mn2)-6(m2n-mn2) (注意第二个括号前有因数6) =6m2n-5mn2-2m2n+3mn2 (去括号与分配律同时进行) =(6-2)m2n+(-5+3)mn2 (合并同类项) =4m2n-2mn2 例2.已知:A=3x2-4xy+2y2,B=x2+2xy-5y2 求:(1)A+B (2)A-B (3)若2A-B+C=0,求C。 解:(1)A+B=(3x2-4xy+2y2)+(x2+2xy-5y2) =3x2-4xy+2y2+x2+2xy-5y2(去括号) =(3+1)x2+(-4+2)xy+(2-5)y2(合并同类项) =4x2-2xy-3y2(按x的降幂排列) (2)A-B=(3x2-4xy+2y2)-(x2+2xy-5y2) =3x2-4xy+2y2-x2-2xy+5y2 (去括号) =(3-1)x2+(-4-2)xy+(2+5)y2 (合并同类项) =2x2-6xy+7y2 (按x的降幂排列) (3)∵2A-B+C=0 ∴C=-2A+B =-2(3x2-4xy+2y2)+(x2+2xy-5y2) =-6x2+8xy-4y2+x2+2xy-5y2 (去括号,注意使用分配律) =(-6+1)x2+(8+2)xy+(-4-5)y2 (合并同类项) =-5x2+10xy-9y2 (按x的降幂排列) 例3.计算: (1)m2+(-mn)-n2+(-m2)-(-0.5n2) (2)2(4an+2-an)-3an+(an+1-2an+1)-(8an+2+3an) (3)化简:(x-y)2-(x-y)2-[(x-y)2-(x-y)2] 解:(1)m2+(-mn)-n2+(-m2)-(-0.5n2) =m2-mn-n2-m2+n2 (去括号) =(-)m2-mn+(-+)n2 (合并同类项) =-m2-mn-n2 (按m的降幂排列) (2)2(4an+2-an)-3an+(an+1-2an+1)-(8an+2+3an) =8an+2-2an-3an-an+1-8an+2-3an (去括号) =0+(-2-3-3)an-an+1 (合并同类项) =-an+1-8an (3)(x-y)2-(x-y)2-[(x-y)2-(x-y)2] [把(x-y)2看作一个整体] =(x-y)2-(x-y)2-(x-y)2+(x-y)2 (去掉中括号) =(1--+)(x-y)2 (“合并同类项”) =(x-y)2 例4求3x2-2{x-5[x-3(x-2x2)-3(x2-2x)]-(x-1)}的值,其中x=2。 分析:由于已知所给的式子比较复杂,一般情况都应先化简整式,然后再代入所给数值x=-2,去括号时要注意符号,并且及时合并同类项,使运算简便。 解:原式=3x2-2{x-5[x-3x+6x2-3x2+6x]-x+1} (去小括号) =3x2-2{x-5[3x2+4x]-x+1} (及时合并同类项) =3x2-2{x-15x2-20x-x+1} (去中括号) =3x2-2{-15x2-20x+1} (化简大括号里的式子) =3x2+30x2+40x-2 (去掉大括号) =33x2+40x-2 当x=-2时,原式=33×(-2)2+40×(-2)-2=132-80-2=50 例5.若16x3m-1y5和-x5y2n+1是同类项,求3m+2n的值。 解:∵16x3m-1y5和-x5y2n+1是同类项 ∴对应x,y的次数应分别相等 ∴3m-1=5且2n+1=5 ∴m=2且n=2 ∴3m+2n=6+4=10 本题考察我们对同类项的概念的理解。 例6.已知x+y=6,xy=-4,求: (5x-4y-3xy)-(8x-y+2xy)的值。 解:(5x-4y-3xy)-(8x-y+2xy) =5x-4y-3xy-8x+y-2xy =-3x-3y-5xy =-3(x+y)-5xy ∵x+y=6,xy=-4 ∴原式=-3×6-5×(-4)=-18+20=2 说明:本题化简后,发现结果可以写成-3(x+y)-5xy的形式,因而可以把x+y,xy的值代入原式即可求得最后结果,而没有必要求出x,y的值,这种思考问题的思想方法叫做整体代换,希望同学们在学习过程中,注意使用。 练习 (一)计算: (1)a-(a-3b+4c)+3(-c+2b) (2)(3x2-2xy+7)-(-4x2+5xy+6) (3)2x2-{-3x+6+[4x2-(2x2-3x+2)]} (二)化简 (1)a>0,b<0,|6-5b|-|3a-2b|-|6b-1|初一数学题—整式的加减
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