2 x 2 y=根号20,x不等于y,求3x y(x-y)-3y x(x-y)
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(x+y)(xy)=x^2y+xy^2=-8原式=-7
x^2+根号2y=根号3,y^2+根号2x=根号3;两式相减;(x-y)(x+y-根号2)=0;x不等于y,x+y=根号2;两式相加:x^2+y^2+根号2(x+y)=2根号3;(x+y)^2-2xy
x+y=根号2x+根号2y=y+根号2xx-y+根号2y-根号2x=0(x+y)(x-y)+根号2(y-x)=0(x-y)(x+y-根号2)=0x+y=根号2
(3x2y-2xy2)-(xy2-2x2y)=3x2y-2xy2-xy2+2x2y=5x2y-3xy2当x=-1,y=2时,原式=5×(-1)2×2-3×(-1)×22=10+12=22.
[2x(x2y-xy2)+xy(xy-x2)]÷x2y=[2x3y-2x2y2+x2y2-x3y]÷x2y=x-y,把x=2013,y=2012代入上式得:原式=x-y=2013-2012=1.
原式=2x2y+2xy-3x2y-3xy-4x2y=-5x2y-xy当x=-2,y=12时,原式=-9.
原式=4x2y-6xy+3(4xy-2)+x2y+1=5x2y+6xy-5当x=2,y=-12时,原式=5×4×(-12)+6×2×(-12)-5=-21.
解-x²y-xy²=-xy(x+y)=-2×5=-10
化简得:9-12Y^2+6Y+4+12Y^2+4Y-10-10Y+X-Y+1=X-Y+4带入X、Y值得:=3
x^2+√2y=√3y^2+√2x=√3两式相减x^2-y^2+√2y-√2x=0(x-y)(x+y)-√2(x-y)=0(x-y)(x+y-√2)=0x不等于yx+y-√2=0x+y=√2x^2+√
(X+Y)2=1402X2Y*3=14400(X+Y)2=140→X+Y=70→Y=70-X①2X2Y*3=14400→XY=1200②把①代人②得:X(70-X)=1200X²-70X+1
原式=5xy2-2x2y+3xy2-2x2y=8xy2-4x2y,∵(x-2)2+|y+1|=0,∴x-2=0,y+1=0,即x=2,y=-1,则原式=16+16=32.
x=±1,y=±3,z=±2xyzz>y则0>x>z>yx=-1,y=-3,z=-2,x2y-[4x2y-(xyz-x2z)-3x2z]-2xyx=x2y-4x2y+xyz-x2z+3x2z-2xyx
x²+√2y=√3……①y²+√2x=√3……②①式减②式x²-y²-√2(x-y)=√3(x+y)(x+y)=√2(x-y)……③∵x不等于y∴x-y≠0∴③
原式=2x2y-2xy2-[-3x2y2+3x2y+3x2y2-3xy2]=2x2y-2xy2+3x2y2-3x2y-3x2y2+3xy2=2x2y-3x2y-2xy2+3xy2+3x2y2-3x2y
代入x=-1,y=1,2x^y-(5xy^-3x^y)-x^=2*(-1)^*1-{5*(-1)*1^-3*(-1)^*1}-(-1)^=2-(-5-3)-1=9备注:2^表示2的平方
由题意得(x-2)平方+(y-2)平方+(x-y)平方=0,故x=y=2,故x平方y=8
原式=2x2y+2xy-3x2y+3xy-4x2y=-5x2y+5xy,当x=-1,y=1时,原式=-5×(-1)2×1+5×(-1)×1=-5-5=-10.
原式=-xy(x-y),当x-y=3,xy=-2时,则原式=-3×(-2)=6.故答案为:6.
如果x,y符号相反,绝对值相等,即y=-x,代入原方程组,得3x-2x=m+1,4x-2x=m-1,即x=m+1,2x=m-1解之,2(m+1)=m-1,得m=-3如果x比y大1,即x=y+1,代入原