先化简,再求值5x²-﹙3y² 5x²﹚ ﹙4y² 7xy﹚

（3x-2y）2-（5x+y）（5x-y）=9x2-12xy+4y2-（25x2-y2）=9x2-12xy+4y2-25x2+y2=-16x2-12xy+5y2当x=2，y=-1时，原式=-16×22

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

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

3x²y-【5x²y+2（x²y-1/2）+x²y】+6x²y=3x²y-【5x²y+2x²y-1+x²y】+

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

[-(xy)/(x-y)^2]^4*[(x^2-xy)/x]^3*x^4/y^10÷[x/(xy-y^2)]^5=(x^4y^4)/(x-y)^8*(x-y)^3*x^4/y^10*[y^5(x-y)

:[(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，

是{（x+y）2-（x+y）（x+3y）-5y}/2y=【（x+y）（2-x-3y）-5y】/2y=(x+y)(2-x-3y)/5y-2.5带入数字（-2+1/2）(2+2-1.5)/2.5-2.5=

先化简,再求值：(1)(3x-5y)+(-3x+y),其中x=5,y=3;原式=3x-5y-3x+y=-4y=-12(2)7x-[-2x-(8x-1)],其中x=-2原式=7x-(-2x-8x+1)=

原式=(3x-y）²-2x（4x-5y）-(x+2y)²=9X²-6XY+Y²-(8X²-10XY)-(X²+4XY+4Y²)=9

=5x-{2y-3x+[5x-2y+4x+3y]}=5x-(2y-3x+5x-2y+4x+3y)=5x-2y+3x-5x+2y-4x-3y=-x-3y=1/2+1/2=1

(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+

[(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

原式=-2x(x-2y)把x=-2,y=1/2代入得原式=-12再问：我邻居说是等于-14，你有没有写错啊再答：没错再问：我看看过程再答：(x+2y)²-(x+y)(3x-y)-5y&sup

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.

原式=-10/3√12x^2*3x/y*x/4y=-10x^2/y=-10/2=-5

(1)原式=9x^2-6xy+y^2-5x^2+5xy=4x^2-xy+y^2=4*0.2^2-0.2*0.1+0.1^2=0.15(2)原式=(2a-b)【(2a+b)-3(2a-b)+(3a-b)

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