2.若x3+y3=1000,x2y-xy2=-498,则(x3-y3)+(4xy2-2x2y)-2(xy2-y3)= ----
(x3-y3)dx+xy2dy
应该是x3+y3=1000,x2y-xy2=-496(x3-y3)+(4xy2-2x2y)-2(xy2-y3)=x^3-y^3+4xy^2-2x^2y-2xy^2+2y^3=x^3+y^3+2xy^2-2x^2y=(x^3+y^3)-2(x^2y-x^2y)=1000+2×496=1992
x+y=10,x3+y3=100,则x2+y2=?
x3+y3=(x+y)(x2+y2-xy)=(x+y)((x+y)2-3xy)=100把x+y=10代入 10*(100-3xy)=100解得xy=30 所以有x2+y2=(x+y)2-2xy=10*10-2*30=40
求合并同类项的计算题(越多越好)谢了!!!有点急啊!!!(越快越好啊...
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...
因式分解题
(1)2x2-3x-1 (2)-2x2+5xy+2y2 考点训练:1. 分解下列因式:(1).10a(x-y)2-5b(y-x) (2).an+1-4an+4an-1(3).x3(2x-y)-2x+y (4).x(6x-1)-1 (5).2ax-10ay+5by+6x (6).1-a2-ab-14 b2 *(7).a4+4 (8).(x2+x)(x2+x-3)+2(9).x5y-9xy5 (10).-4x2+3xy+2...
...x3-2xy2+y3)+(-x3+3x2y-y3)的值,其中x=-13,y=-2.甲同学把
(2x3-3x2y-2xy2)-(x3-2xy2+y3)+(-x3+3x2y-y3)=2x3-3x2y-2xy2-x3+2xy2-y3-x3+3x2y-y3=(2-1-1)x3+(-3+3)x2y+(-2+2)xy2+(-1-1)y3=-2y3,故代数式的值与x的取值无关,所以.甲同学把“x=-13”错抄成“x=13”.但他计算的结果是正确的.
初一数学有个叫做简便运算,解方程,合并同类项化简,合并同类项化简求值...
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...
己知x=3-2倍根号2,y是x倒数,则x2y-xy2值为
己知x=3-2倍根号2,y是x倒数,则x2y-xy2值为 我来答 你的回答被采纳后将获得: 系统奖励15(财富值+成长值)+难题奖励30(财富值+成长值) 1个回答 #热议# 生活中有哪些成瘾食物? 陶永清 2015-06-12 · TA获得超过10.6万个赞 知道大有可为答主 回答量:1.5万 采纳率:66% 帮助的人:5709...
因式分解
=(x2+x+5)(x2+x-2)=(x2+x+5)(x+2)(x-1).综合除法令多项式f(x)=0,求出其根为x1,x2,x3,……,xn,则该多项式可分解为f(x)=a(x-x1)(x-x2)(x-x3)……(x-xn) .例如在分解2x4+7x3-2x2-13x+6时,令2x4 +7x3-2x2-13x+6=0,则通过综合除法可知,该方程的根为0.5 ,-3,-2,...
先化简,再求值
19。 (4xy2-2x2y) - ()= X3-2x2y +4 XY2 + Y3。21。已知A = X3-2×2 + X-4,B = 2×3-5X 3,计算A + B = ___。22。已知A = X3-2×2 + X-4,B = 2×3-5X 3,计算AB = ___。23。若a = -0.2,B = 0.5,代数表达式 - (| A2B | - | AB2 |)...
化简求值题带答案
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)...