2X² xy-y²-4x 5y-6
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根据题意得,x+1=0,2x-y+4=0,解得x=-1,y=2,∴x5y+xy5=(-1)5×2+(-1)×25=-2-32=-34.故答案为:-34.
3xy是3x原式=(x-3y)(x+2y)+3x+y+2十字相乘x-3y2×x+2y1所以原式=(x-3y+2)(x+2y+1)
个人觉得,不如直接计算6x-2y=-12-1=-132xy^2=2*(-2)*1/4=-1所以(6x-2y)*3/2xy^2=(-13)^3/(-1)=2197xy=-1(xy-3)(xy+1)=0(
(1)4x2m+1y的系数是4,次数是2m+2;-5x2y2的系数是-5,次数是4;-31x5y的系数是-31,次数是6;(2)由(1)可得2m+2=8,解得m=3.
原式=3xy+6y-xy+6x=2xy+6(x+y)=2*(-2)+6*4=24-4=20
x^+2xy+y^+4=16(x+y)²=16-4=12(1)x^-2xy+y^=16(x-y)²=16(2)(1)-(2)2y*2x=-4xy=-1(3xy+6y^)+|x^-(
Solution:x^2-2xy+3y^2=9(1)4x^2-5xy+6y^2=30(2)Eq(1)*5-Eq(2)*2,wehavex^2-y^2=5(3)Eq(2)-Eq(1),wegetx^2+
(-3x^y+2xy)-(4x^+xy)=-3x^y+2xy-4x^-xy=-3x^y+xy-4x^所以填上-3x^y+xy-4x^
3(xy+2y)-(xy-6x)=3xy+6y-xy+6x=2xy+6(x+y)=2×(-2)+6×4=-4+24=20
解3x²y+6xy-4x-8=(3x²y-4x)+(6xy-8)=x(3xy-4)+2(3xy-4)=(x+2)(3xy-4)
[3xy(1-x)-6xy(x-1/2)]*2x*(-xy)平方=(3xy-3x²y-6x²y+3xy)(2x³y²)=12x^4y³-18x^5y&
(5xy+4x+7y)+(6x-3xy)-(4xy-3y)=5xy+4x+7y+6x-3xy-4xy+3y=(5xy-3xy-4xy)+(4x+6x)+(7y+3y)=-2xy+10x+10y=-2x
因为xy(y^2+y)-y^2(xy+2x)-3xy=xy^3+xy^2-xy^3-2xy^2-3xy=-xy^2-3xy根据x+y=4,x-y的绝对值=6,可以写出两个方程组x+y=4,x-y=6和
错在第(4)步.∵x>y,∴y-x<0.不等式两边同时除以负数y-x,不等号应改变方向才能成立.
x²-xy+3y-3x=x(x-y)-3(x-y)=(x-y)(x-3)2x²+xy-y²-4x+5y-6=(2x-y)(x+y)-4x+5y-6=(2x-y+2)(x+
已知x+xy=-2,xy-y=-6则X+Y=42x{-4y-3[(x+xy)²+x]-½[(y-xy)²-2y]=2x{-4y-3[(-2)²+x]-&fr
-3(2x-xy)-4(-6+xy+x)=-6x+3xy+24-4xy-4x=-10x-xy+24=-10+1+24=15先化简.后代入求值
x^2y+4xy+4y=y(x²+4x+4)=y(x+2)²
原式=-x²y+2xy²+2x²y²-4xy³-3x³+27x³y-18x²y²+2x²y-18x&
再问:能把第三题重新发一遍吗?再答:这三个题本质上式连在一起的再答:这道题应该是希望杯的试题