已知2x2+5xy-3y2=0且xy不等于0,求x:y的值已知2x2+5xy-3y2=0且xy不等于0,求xy的值

已知x2-3xy=-5,xy+y2=3,求x2-2xy+y2. 已知2x2+5xy-3y2=0且xy不等于0,求x:y的值已知2x2+5xy-3y2=0且xy不等于0,求xy的值 已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2= 解方程组 x2 -2xy -y2 =1 2x2 -5xy -3y2 =0 若X2+xy-2y2=0,则（x2+3xy+y2)/x2+y2=? 已知xy不等于0,且3x2-2xy-8y2=0,求x/y的值? 已知x2+y2=7,xy=-2,求5x2—3xy—4y2—11xy—7x2+2y2的值 已知X2+y2=7,Xy=-2,求多项式5X2一3Xy-4y2-11Xy-7X2+2y2的值. 已知x2+y2 =7,xy=-2.求5x2 -3xy-4y2 -11xy-7x2 +2y2 已知x2-2xy=3y2且x,y为非零实数 求：（1）2x+y/x-2y (2)2x2-3y2+5xy/x2+xy+y2 已知X2次方+XY=3,XY+Y2次方=-2,求下例值:X2次方-Y2次方 已知x2+y2+4x-2y+5=0,求x2+2xy+y2值 已知x/y=3/5,求 (x2-xy+2y2)/(x2+2xy-y2)的值 已知:x2+y2=7,xy=-2.求7x2-3xy-2y2-11xy-5x2+4y2已知:x2+y2=7,xy=-2.求7x2-3xy-2y2-11xy-5x2+4y2 已知x2+xy=3,y2+xy=-2,则2x2-xy-3y2=多少 已知X2次方+XY=3,XY+Y2次方=-2,求下例值:2X2次方-XY-3Y2次方 已知X2次方+XY=3,XY+Y2次方=-2,求下例值:X2次方+4XY+3Y2次方 已知：A=2x2－5xy－3y2,B=2x2+3xy－4y2,且A+B－C=0,求C.写出过程和结果