若5x²-7xy-6y²=0 y不等于0

若X方-2XY+Y方+1XY-11=0则：x-y=0.而且xy=1所以,x=y=1,或者,x=y=-1所以,x/y=1X方+6XY+9Y方分之X方-25Y方*5X-25Y分之X+3Y=（x²

x-5xy+6y=0(√x-2√y)(√x-3√y)=0所以√x=2√y,√x=3√yx=4y或x=9y原式=(8y)/(9y)=8/9或=(14y)/(20y)=7/10

首先化简：原式=7x+4y+xy-5y-6x+6xy=(x-y)+7xy因为,x-y=5,-xy=3所以原式=5-21=-16楼上忘记加负号了~

解题思路：根据题意，由完全平方公式的知识可求解题过程：varSWOC={};SWOC.tip=false;try{SWOCX2.OpenFile("http://dayi.prcedu.com/inc

你好：原式=（7x+4y+xy)-(5y+6x-6xy)……………………把“6”乘进去=7x+4y+xy-5y-6x+6xy=x-y+7xy因为x-y=5,-xy=3所以xy=-3所以,原式=5+7乘

x=-1,y=-6或x=6,y=1代入式子得x^2-xy^2=37或30x^2y+xy^2=-42或42

(x+y)^2=36x^2+y^2+2xy=36x^2+y^2=36-2*2.75=30.5(x-y)^2=x^2+y^2-2xy=30.5-2*2.75=25x-y=5或者-5已知x-y>0x-y=

(x*x+y*y)(x*x+y*y)-4x*x*y*y=(x^4-2x^2y^2+y^4)=(x^2-y^2)^2=0x^2=y^2x/y=±1(x*x+5xy+y*y)/(x*x+2xy+y*y)=

∵/x+y-7/（绝对值）+(xy-5)平方=0∴x+y-7=0xy-5=0∴x+y=7xy=5∴x²+y²=(x+y)²-2xy=7²-2×5=39

(3xy+2)^2+|7-x-y|=0,则3xy+2=0,7-x-y=0,即x+y=7,xy=-2/3(5xy+10y)-[-5x-(4xy-2y+3x)]=5xy+10y-(-5x-4xy+2y-3

先把代数式（5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)化简（5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)=5XY+4X+7Y+6X-3XY-4XY+3Y=-2XY+10X+1

（7xy+4x-7y）+(6x-3xy)-(3y+4xy)=7xy+4x-7y+6x-3xy-3y-4xy=10x-10y=10（x-y）=10*3=30

-2x+6xy-2y/(7x+5y)-9xy-(3x+y)=[3(x+y)-x-y]/[7x+5y-9/2(x+y)-3x-y]=2(x+y)/[-1/2(x+y)]=-4

（7x+4y+xy）-6（5/6y+x-xy）=7x+4y+xy-5y-6x+6xy=x-y+7xy=5+7×(-3)=-16

把括号打开7X+4Y+XY-5Y-6X+6XY=X-Y+7XY=5+7*(-3)=-16

(7x+4y+xy)-6(六分之五y+x-xy)=7x+4y+xy-5y-6x+6xy=x-y+10xy把x-y=5和-xy=3代入x-y+10xy=5+10*(-3)=5-30=-25所以原式的值是

x²-5xy+6y²=0两边同时除以y²得x²/y²-5x/y+6=0(x/y)²-5(x/y)+6=0(x/y-2)(x/y-3)=0x/

x+y=5xy（2x-3xy+2y)/(x+2xy+y）=[2（x+y）-3xy]/[(x+y)+2xy]=(2×5xy-3xy)/(5xy+2xy)=7xy/7xy=1再问：若x＋1/x＝3,求(x

x^2y+xy^2＝xy×（x+y）＝6×5＝30

因为,x-y=3xy所以：-3x+6xy+3y/[(7x-5y)-9xy-(3x-y)]=[-3(x-y)+6xy]/[(7x-5y)-9xy-(3x-y)]=[-3*3xy+6xy]/[7x-5y-