已知p=x-y分之x的平方-x-y分之y的平方

（1）x^2+3xy-4y^2=0十字相乘：(x+4y)(x-y)=0则：x=-4y,或x=y；当x=-4y时,(x-2y)/(x+2y)=-6y/(-2y)=3；当x=y时,(x-2y)/(x+2y

3x^2+xy-2y^2=(3x-2y)(x+y)=0x=-2y/3,或x=-y但由于你要求的式子中分母里有X平方-Y平方x=-y舍去其他就代入吧

x/y=2平方x²/y²=4原式分子分母同除以y²所以原式=(x²/y²-x/y+3)/(x²/y²+x/y+6)=(4-2+3)

令x=y+3变成x-y=3把x-y=3带到x-y里4分之一(x-y)的平方-0.3(x-y)+0.75(x-y)的平方+10分之3(x-y=2.25-0.9+6.75+0.9=9

x=y+3∴x-y=34分之一(x-y)的平方-0.3(x-y)+0.75(x-y)的平方+10分之3(x-y）-2（x-y）+7=(0.25+0.75)(x-y)²+(-0.3+0.3-2

(x-y)/(x+y)=(x-y)(x+y)/[(x+y)^2]=(x^2-y^2)/[x^2+y^2+2xy]=2xy/[x^2+y^2+x^2-y^2]=2xy/(2x^2)=y/xx^2-y^2

x^2+y^2-4x-6y+13=0(x^2-4x+4)+(x^2-6y+9)=0(x-2)^2+(y-3)^2=0所以(x-2)^2=0,(y-3)^2=0x-2=0,y-3=0x=2,y=3xy/

x/y=7/2(x²-3xy+2y²)/(x²+2xy+y²)=[(x/y)²-3(x/y)+2]/[(x/y)²+2(x/y)+1]=[(

已知5x-4y=0,切xy≠0,x/y=4/5;求(x平方-y平方)分之(x平方+y平方)-(x-y)分之(x+y)的值=(x²+y²)/(x²-y²)-(x+

x/y=1/2y=2x(x^2+2xy+y^2)/(x^2-xy+y^2)=(x^2+2x*2x+(2x)^2)/(x^2-x*2x+(2x)^2)=9x^2/3x^2=3

y分之x=2分之1y=2x所以原原式=(x²-2x²-8x²)分之（x²＋4x²＋4x²）=-9分之9=-1

x的平方+y的平方=2xyx的平方+y的平方-2xy=0(x-y)^2=0x=y3x+y分之15x-y=14x/4x=7/2

x的平方+2xy+y的平方分之x的平方-y的平方=(x+y)(x-y)/(x+y)²=(x-y)/(x+y)∵x+y=2,x-y=1∴原式=1/2

X的平方+Y的平方-6X-8Y+25=0,整理就是x²+y²-6x-8y+9+16=0即x²-6x+9+y²-8y+16=0于是（x-3)²+（y-4

x的平方+xy+y的平方=0x的平方+y的平方=-xyx/y+y/x=-1如追加其它问题,采纳本题后点击想我求助,

P=(x²-y²)/(x-y)=(x+y)(x-y)/(x-y)=x+yQ=x²+2xy+y²-2xy-2y²=x²-y²所以x=

y分之x=2分之1y=2x所以原原式=(x²-2x²-8x²)分之（x²＋4x²＋4x²）=-9分之9=-1

x²+y²=-2xyx²+2xy+y²=0(x+y)²=0x+y=0所以x=-y所以(x-3y)/(x+3y)=(-y-3y)/(-y+3y)=-4y

X平方+4Y的平方=4XYx^2-4xy+4y^2=0(x-2y)^2=0x=2yX-Y分之X+2Y=(2y+2y)(2y-y)=4y/y=4

1.整理得到算式[2x-x+y]/[x^2-y^2]=[x+y]/[x+y][x-y]=1/[x-y]代入得到1/72.整理得到[1-3/(a+2)]/[(a^2-2a+1)/(a^2-4)]=[(a