计算(x+y/x-y + 4xy/y2-x2)(x2-9y2)/(x2+2xy-3y2)
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
2x2+xy-3y2+x+4y-1因式分解
已知:x=3,y=-5,x2-2xy+y2/x2-y2的值是
已知实数x,y满足x2+xy+y2=3,则x2-xy+y2的最小值
x2-2xy+y2+3x-3y+2.
25(x2+ 2xy +y2)-9(x2-2xy+y2)因式分解.x2,y2是x平方,y平方的意思.2xy就是2xy.快
已知x2+4y2+x2y2-6xy+1=0,求 x4-y4/2x-y 乘 2xy-y2/xy-y2 除以(x2+y2/x
已知2x-3*根号(xy)-2y=0(x>0),则x2+4xy-16y2除以2x2+xy-9y2的值是多少?
x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
先化简再求值:-(x2+y2)+[-3xy-(x2-y2)],其中x=-1,y=2.
若x<y<0,则x2−2xy+y2+x2+2xy+y2=( )
已知X2-2x+y2+6y+10=0,求(x2-2xy)/(xy+y2)的值