当x+y=-3,求(2x2+xy+3y2)-(x2-xy+2y2)的值,速求!
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
x(x-1)-(x2-y)=-3,求x2-y2-2xy的值
x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
已知x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
已知x+y=4,xy=2,求x2+y2+3xy的值.
已知(x+y)2=25,xy=3,求x2+y2求x2+y2的值答案是?
若X2+Y2-2X-6Y+10=0 ,求(x2-y2)/xy的值
已知非零实数x,y满足:x2+xy-2y2=0,求(x2+3y+y2)/(x2+y2)的值
当x=2,y=1 求{(x2+y2)/(x2-2xy+y2)+(2)/xy÷[(1/x)-(1/y)]}÷(x+y)的值
已知X2-2x+y2+6y+10=0,求(x2-2xy)/(xy+y2)的值
已知:x=3,y=-5,x2-2xy+y2/x2-y2的值是
已知x2;+xy=3,xy+y=-2,求代数式2x2;-xy-3y2;的值