先化简,再求值:(1 x-y+2x²-xy)÷x+2 2x-搜答案-神马作文网

先化简,再求值：已知,化简xy(x+y的平方）-y的平方(xy-x)+2x(x-y的平方),并求它们的值.x+y=5,2x-y=1＝＝>x＝2,y＝3xy(x+y^2)-y^2(xy-x)+2x(x-

3（x-y）-2（x+y）+2=3x-3y-2x-2y+3=x-5y+2，∵x=-1，y＝34．，∴x-5y+2=-1-5×34+2=-114．

[(X+2Y)平方-(X+Y)(3X-Y)-5Y平方]除以（2X）=(x²+4y²+4xy-3x²+xy-3xy+y²-5y²)/(2x)=(-2x&

[(x+2y)²-2(x+y)(x-y)-5y²]÷(2x)=x²+4xy+4y²-x²+y²-5y²=4xy当x=-2,y=1/

原式=(x-y)(x+y)-(x+y)^2+2y(y-x)=(x+y)(x-y-x-y)-2y(x-y)=-2y(x+y)-2y(x-y)=-2y(x+y+x-y)=-2y×(-2x)=4xy将x=1

先化简,再求值:【1/（x-y）】-【1/（x+y）】/【xy²/（x²-y²）】,其中x=√2+1,y=√2-1【1/（x-y）】-【1/（x+y）】/【xy²

:[(3x-y)(2x+4y)-(x+2y)(5x-2y)]/4=(x+2y)(6x-2y-5x+2y)/4=x(x+2y)/4当x=-2,y=1时原式=-2(-2+2)/4=0再问：补上一点写漏了，

[x²+y²-(x-y)²+2y(x-y)]÷4y=[x²+y²-(x²-2xy+y²)+2y(x-y)]÷4y=(x²

原式=（x²-y²）/(x-y)=(x+y)（x-y)/(x-y)=x+y其他的自己带入即可

(2x-y)(2x+y)-(2y+x的2次方)(2y-x的2次方)=4x²-y²-(4y²-x^4)=x^4+4x²-5y²=1+4-5×4=-15

x√(1/x)+√4y-2分之√x+1/y√y³=√x+2√y-√x/2+√y=3√y当x=4,y=1/9时,原式=3√y=1

原式=8x³+4x²y-4x²y-2xy²+2xy²+y³-8x³+x²y+8xy²-y³=x

原式=(x-y)²/(x+y)²(x+y)^4/(x-y)²*1/(x+y)=x+y=-3

我用x2表示的x的平方1,(x-y)2=x2-2xy+y2,(x+y)(x-y)=x2-y2,所以原式=(2x2-2xy)/2x=x-y=12,=xy+y2+x2-y2-x2=xy=-13,=x2-x

(x-y)^2+7(x+y)-11(x-y)^2-8(x+y),=-10(x-y)²-(x+y)当x+y=-3,x-y=-1时=-10*(-1)²-(-3)=-10+3=-7

再答：再答：看后面这个图再答：不懂可以问我

为你提供精确解答先化简：（x^2-y^2-x^2+2xy-y^2+2xy-6y^2)/(-4y)=(4xy-8y^2)/(-4y)=-x+2y=-1-4=-5其他的正在为你解答.

(3x-y)²+(3x+y)(3x-y)=(3x-y+3x+y)(3x-y)=6X(3X-y)=6(3+2)=30

(1)=2x-2y-4x-y=-2x-3y=(-2)*(-1/12)-3*(-1/6)=1/6+3/6=2/3(2)=4a+3a²-3+4a三次方+a-4a三次方）=3a²+5a-

2(2x-y)-3(2y-1/3y)=4x-2y-6y+y=4x-7y=4*(-3)-7*1=-12-7=-19