先化简,再求值. 2(x-y)(x+y)-(2x-y)(x+2y),-搜答案-神马作文网

解(x-2y)(2y-x)+(2x+y)(2x-y)-(x-2y)(2x+y)=(2xy-x²-4y²+2xy)+(4x²-y²)-(2x²+xy-4

[（5X+2Y)(3X+2Y)+(X-2Y)(X+2Y)]/4X=[15x²+10xy+6xy+4y²+x²-4y²]/4x=[16x²+16xy]/

x-3（x+2y）+4（2y-x）=x-3x-6y+8y-4x=-6x+2y=-6×（-3）+2×2=18+4=22

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

[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)-(2x-y)^2+2y^2,=4x²-y²-4x²＋4xy-y²＋2y²=4xy其中xy=2012所以原式=4×2012=8

原式=x2+4xy+4y2-2（x2-y2）+2xy-6y2=x2+4xy+4y2-2x2+2y2+2xy-6y2=-x2+6xy，当x=-2，y=12时，原式=-（-2）2+6×（-2）×12=-4

1.先化简,再求值:(2X+Y)^2-(2X-Y)(X+Y)-2(X-2Y)(X+2Y),其中X=0.5,Y=-2原式=4x^2+4xy+y^2-(2x^2+2xy-xy-y^2)-2(x^2-4y^

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

x+y也有平方的原式=(x²-2xy+y²-x²-2xy-y²)/2xy=-4xy/2xy=-2再问：我是怎么写的最后【-4xy】/（2x）可是再后=-2y再答

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

(3x-2y)^2-(4x^2-y^2)-(4x^2-6xy)=(9x^2-12xy+4y^2)+y^2-8x^2+6xy=x^2-6xy+5y^2=1/9+6/6+5*1/4=1/9+9/4=(4+

(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

[(5x+3y)^2-(3y+x)(3y-x)^16]/(4x)=【25x^2+30xy+9y^2-9y^2+x^2]/4x=(26x^2+30xy)/4x=13x/2+15y/2=13/2-15/2

(√x+1)+y^2+4=-4y√(x+1)+y²+4y+4=0√(x+1)+(y+2)²=0∴x+1=0y+2=0∴x=-1y=-2(2x-y)(y+x)-(x-2y)(2y+x

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

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