1樓:充珈藍石
1、x-(x-1)/2=2-(x-2)/3 x-x/2+1/2=2-x/3+2/3 x/2+x/3=2+2/3-1/2 5x/6=13/6 x=13/5 2、(x-1)/2-(2x-7)/6=(4x-5)/3-1 x/2-1/2-x/3+7/6=4x/3-5/3-1 7/6-1/2+1+5/3=4x/3+x/3-x/2 10/3=7x/6 x=30/7 3、3(2x-1)=2(1-x)-1 6x-3=2-2x-1 8x=2-1+3 8x=4 x...
2樓:
3ab-4ab+8ab-7ab+ab 23a3bc2-15ab2c+8abc-24a3bc2-8abc 2y+(-2y+5)-(3y+2) (2x2-3xy+4y2)+(x2+2xy-3y2) 2a-(3a-2b+2)+(3a-4b-1) 2x-(x+3y)-(-x-y)-(x-y) 2x+2y-[3x-2(x-y)] 5-(1-x)-1-(x-1) 3x-2x2+x-4+2x3-5x+3 3x-2x+x-4-(2x3-5x+3) -(2x2-y2)...
七年級,簡單些的先化簡再求值數學計算題,並帶答案,二十道,急急急急急!!!求幫忙qaq
3樓:小鈴鐺
9x 6x^2 -3(x-2/3x^2).其中x=-2 9x 6x -3(x-2/3x) =9x 6x-3x 2x =8x 6x =8×(-2) 6×(-2) =32-12 =20 1/4(-4x^2 2x-8)-(1/2x-1),其中x=1/2 1/4(-4x 2x-8)-(1/2x-1) =-x 1/2x-2-1/2x 1 =-x-1 =-(1/2)-1 =-1/4-1 =-5/4 (1) 5a-2b 3b-4a-1 a= -1 b=2 (2)7x-3x-2x-2x=5=6x x= -2 (3)2x―[6-2(x-2)] 其中 x=-2 (4).(5a+2a-3-4a)-(-a+3a-a),其中a=-2 (5)3x 4x-2x-x x-3x-1 其中x= -3 (6)-3[y-(3x2-3xy)]-[y 2(4x2-4xy)],其中x=2, y=1/2 (7)2x-3xy y-2xy-2x 5xy-2y 1 其中x=22/7 (8)2xy 4xy-3xy-5xy 其中x=1 y= -1 (9)9x 6x2 -3(x-2/3x2).其中x=-2 (10)1/4(-4x 2x-8)-(1/2x-1) 其中x=1/2 (11)3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz,其中x=-2,y=-3,z=1, 、(12)(5a^2-3b^2) (a^2 b^2)-(5a^2 3b^2),其中a=-1,b=1 (13)2(a^2b ab^2)-2(a^2 b-1)-2ab^2 -2其中a=-2,b=2 (14)(3x-5y) (-3 y)其中x=5,y=3 (15).
【(x 1)(x 2)-2】÷x,其中x=-3
1) 66x+17y=3967
25x+y=1200
答案:x=48 y=47
(2) 18x+23y=2303
74x-y=1998
答案:x=27 y=79
(3) 44x+90y=7796
44x+y=3476
答案:x=79 y=48
(4) 76x-66y=4082
30x-y=2940
答案:x=98 y=51
(5) 67x+54y=8546
71x-y=5680
答案:x=80 y=59
(6) 42x-95y=-1410
21x-y=1575
答案:x=75 y=48
(7) 47x-40y=853
34x-y=2006
答案:x=59 y=48
(8) 19x-32y=-1786
75x+y=4950
4樓:從潔雅
……先把原式子化簡,再帶入即可
初一數學題,先化簡再求值的題帶答案
5樓:匿名使用者
3ab-4ab+8ab-7ab+ab=______.5a+3b-2a+(2b+3b)=______2a-b2+c-d3=2a+( )-d3=2a-d3-( )=c-( ).
2x-(x+3y)-(-x-y)-(x-y)=( )=2x-x+3y+x+y-x+y
=x+5y
已知x<0,y<0,化簡|x+y|-|5-x-y|=______..-7x2+6x+13x2-4x-5x2=______.3b+5a-5b+10b=______
化簡代數式x-[y-2x-(x+y)]等於______.
6樓:8冰藍水蜜桃
①2a-(3a-2b+2)+(3a-4b-1) =( )=2a-3a+2b-2+3a-4b-1
=(2-3+3)a+(2-4)b+(-2-1)=2a-2b-3
②5-(1-x)-1-(x-1)=( )=5-1+x-1-x+1
=4③2x-(x+3y)-(-x-y)-(x-y)=( )=2x-x+3y+x+y-x+y
=x+5y純手工
7樓:一生一世攜白頭
3ab-4ab+8ab-7ab+ab=ab a=1b=2 ab=1x2= 2
2x-(x+3y)-(-x-y)-(x-y)=2x-x-3y+x+y-x+y=x-y x=6 y=2 x-y=6-2=4
8樓:清風習來
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,計算a+b=______.
22.已知a=x3-2x2+x-4,b=2x3-5x+3,計算a-b=______.
23.若a=-0.2,b=0.5,代數式-(|a2b|-|ab2|)的值為______.
25.乙個多項式減去3m4-m3-2m+5得-2m4-3m3-2m2-1,那麼這個多項式等於______.
26.-(2x2-y2)-[2y2-(x2+2xy)]=______.
27.若-3a3b2與5ax-1by+2是同類項,則x=______,y=______.
28.(-y+6+3y4-y3)-(2y2-3y3+y4-7)=______.
29.化簡代數式4x2-[7x2-5x-3(1-2x+x2)]的結果是______.
30.2a-b2+c-d3=2a+( )-d3=2a-d3-( )=c-( ).
31.3a-(2a-3b)+3(a-2b)-b=______.
32.化簡代數式x-[y-2x-(x+y)]等於______.
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)等於______.
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.若乙個多項式加上-3x2y+2x2-3xy-4得
2x2y+3xy2-x2+2xy,
則這個多項式為______.
40.-5xm-xm-(-7xm)+(-3xm)=______.
41.當a=-1,b=-2時,
[a-(b-c)]-[-b-(-c-a)]=______.
43.當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2y-x=5時,5(x-2y)2-3(-x+2y)-100=_____
數學七年級先化簡再求值題目,越多越好…(有答案)
9樓:匿名使用者
1.先化簡,再求bai值:du
[(a+b)(a-b) -(a-b)2+2b(a-b)]÷zhi4b,a=2,b=-2.
2.已知x+y=7,xy=2,求①2x2+2y2的值dao;②回(x-y)2的值.
1、a-b,4
2、(答1)90
(2)41
初一上期末數學先化簡再求值的題
10樓:凌月霜丶
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,計算a+b=______.
22.已知a=x3-2x2+x-4,b=2x3-5x+3,計算a-b=______.
初一數學題,初一數學題
解答 酒精溶液裡含酒精 100 72 72 g 加水後酒精溶液總重100 44 144g,此時的酒精質量分數 72 144 100 50 甲乙各取x,y千克。顯然地x y 50.一 甲和乙中含酒精量分別為 x 30 y 80 調配以後的酒精含量為 50 50 25.所以x 30 y 80 25.二 ...
初一數學題,初一數學應用題60題
解 1 設生產a型飲料需要x瓶,則b型飲料需要100 x瓶根據題意 20x 30 100 x 2800 1 40x 20 100 x 2800 2 由 1 20x 3000 30x 2800 10x 200 x 20 由 2 40x 2000 20x 2800 20x 800 x 40 所以x的取值...
初一數學角度題,初一數學題。求角度
因為oa垂直於ob 所以 aob為90度 因為om平分 aob 所以 bom moa 因為 aon平分 aoc 所以 aon noc 所以 mon 0.5 boc 初一數學要因為所以 mon moc noc 1 2 boc 1 2 aoc 1 2 90 aoc 1 2 aoc 45度 mon moc...