计算11²-12²+13²-14²+15²-16&

计算11²-12²+13²-14²+15²-16&

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======以下答案可供参考======供参考答案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。

和我的回答一样，看来我也对了