X加Y=8 X-Y=6 求X Y
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把25拆成16+9(x²-8x+16)+(y²+6y+9)=0(x-4)²+(y+3)²=0平方大于等于0,相加等于0若有一个大于0,则另一个小于0,不成立.所
x-xy=8(1)xy-y=-9(2)则有(1)-(2):X-XY-XY+Y=X+Y-2XY=8-(-9)=17
x^+2xy+y^+4=16(x+y)²=16-4=12(1)x^-2xy+y^=16(x-y)²=16(2)(1)-(2)2y*2x=-4xy=-1(3xy+6y^)+|x^-(
(x-2y)(3+x)=0x-2y=0x=2yx+3=0x=-3y=-3/2(3x^2+3xy)/(3xy-x+6y)=(27+27/2)/(27/2+3-9)=-81/135=-3/5
x²+2xy+4y²+x²y²+1=8xy(x²-4xy+4y²)+(x²y²-2xy+1)=0(x-2y)²
已知x=二分之一,xy(y加y的二次方)减y的二次方(xy-x)+2x(x-y的平方)的值=xy²+xy³-xy³+xy²+2x²-2xy²
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(x+y)(x-y)-y^2+(x-y)^2-(6x^2y-2xy^2)÷2y=(x+y)(x-y)-y^2+(x-y)^2-2y(3x^2-xy)÷2y=(x+y)(x-y)-y^2+(x-y)^2
(x+y+z)²+(x-y-z)(x-y+z)-2·z(x+y)=(x+y)²+2z(x+y)+z²+(x-y)²-z²-2z(x+y)=(x+y)&
把第一个式子分开来看,x的平方-8x+16+y的平方+6Y+9=0,然后就有两个完全平方了,(x-4)的平方+(y+3)的平方=0然后可以得出x=4,y=-3,然后带进去就可以得出答案
x平方+8x+16+y平方+6x+9=0(x+4)平方+(y+3)平方=0∴x+4=0y+3=0∴x=-4,y=-3原式=(x+2y)(x-2y)/(x+2y)平方-x/(x+2y)=(x-2y)/(
x/y+y/x=(x²+y²)/xyx²+y²=(x+y)²-2xy=36-16=20原式=20/8=2.5
(5xy+4x+7y)+(6x-3xy)-(4xy-3y)=5xy+4x+7y+6x-3xy-4xy+3y=(5xy-3xy-4xy)+(4x+6x)+(7y+3y)=-2xy+10x+10y=-2x
xy/x+y=6∴xy=6(x+y)3x-2xy+3y/-x+3xy-y=[3x-12(x+y)+3y]/[-x+18(x+y)-y]=-9(x+y)/17(x+y)=-9/17再问:你在啊?再答:在
已知xy+x+y=6则xy+x+y+1=(x+1)(y+1)=7=7×1因为x,y都是自然数(非负整数)所以x+1,y+1≥1所以只能x+1=7y+1=1即x=6,y=0或x+1=1,y+1=7即x=
(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)=x²-y²-y²+x²-2xy+y²