先化简,再求值(x+5y)(x+4y)
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解(x-2y)(2y-x)+(2x+y)(2x-y)-(x-2y)(2x+y)=(2xy-x²-4y²+2xy)+(4x²-y²)-(2x²+xy-4
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-
[(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+2y)²-2(x+y)(x-y)-5y²]÷(2x)=x²+4xy+4y²-x²+y²-5y²=4xy当x=-2,y=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,
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=
原式=x^2+4xy+4y^2-x^2+y^2-5y^2=4xy代x=-2,y=1/2入得原式=-2*4*1/2=-4
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+
(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
原式=(x^2-4y^2-x^2-8xy-16y^2)/(4y)=-5y-2x=-25-4=-29
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
原式=(x+2)(x+3)x+3•x−3(x+2)(x−2)−1=x−3x−2−x−2x−2=−1x−2;当x=3时,原式=−13−2=2+3.