Question

初一计算

计算11²-12²+13²-14²+15²-16²+17²-18²+19²-20²
快的加分啊！10分钟内啊

Answer 1

1. -3(x2-xy)-x(-2y+2x) ⑵ (-x5)•x3n-1+x3n•(-x)4
2. (x+2)(y+3)-(x+1)(y-2) ⑷ (-2m2n)3•mn+(-7m7n12)0-2(mn)-4•m11•n8
3. (5x2y3-4x3y2+6x)÷6x,其中x=-2,y=2 ⑹ (3mn+1)(3mn-1)-(3mn-2)2
4. 9992-1 ⑻ 20032
5. -2.5×(-4.8)×(0.09)÷(-0.27)
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)＝______．
8．(2x2-3xy+4y2)+(x2+2xy-3y2)=______．
9．2a-(3a-2b+2)+(3a-4b-1)=______．
10．-6x2-7x2+15x2-2x2＝______．
11．2x-(x+3y)-(-x-y)-(x-y)＝______．
12．2x+2y-[3x-2(x-y)]=______．
13．5-(1-x)-1-(x-1)=______．
14．( )+(4xy+7x2-y2)=10x2-xy．
15．(4xy2-2x2y)-( )=x3-2x2y+4xy2+y3．
16．已知A=x3-2x2+x-4，B=2x3-5x+3，计算A+B=______．
17．已知A=x3-2x2+x-4，B=2x3-5x+3，计算A-B=______．
18．若a=-0.2，b=0.5，代数式-(|a2b|-|ab2|)的值为______．
19．一个多项式减去3m4-m3-2m+5得-2m4-3m3-2m2-1，那么这个多项式等于______．
20．-(2x2-y2)-[2y2-(x2+2xy)]=______．
21．若-3a3b2与5ax-1by+2是同类项，则x=______，y=______．
22．(-y+6+3y4-y3)-(2y2-3y3+y4-7)＝______．
23．化简代数式4x2-[7x2-5x-3(1-2x+x2)]的结果是______．
24．2a-b2+c-d3=2a+( )-d3=2a-d3-( )=c-( )．
25．3a-(2a-3b)+3(a-2b)-b=______．
26．化简代数式x-[y-2x-(x+y)]等于______．
27．[5a2+( )a-7]+[( )a2-4a+( )]=a2+2a+1．
28．3x-[y-(2x+y)]=______．
29．化简|1-x+y|-|x-y|(其中x＜0，y＞0)等于______．
30．已知x≤y，x+y-|x-y|=______．
满意请采纳。

Answer 2

11²-12²+13²-14²+15²-16²+17²-18²+19²-20²

=(11+12)(11-12)+(13+14)(13-14)+(15+16)(15-16)+(17+18)(17-18)+(19+20)(19-20)
=-(23+27+31+35+39)
=-(50+31+39+35)
=-(50+70+35)
=-155