已知x+y=7,x-y=5,求x2-y2-2y+2x的值.
已知x+y=7,x-y=5,求x2-y2-2y+2x的值.
已知x2+4x+y2-2y+5=0,求x,y的值.
已知2x+y=7,x2+y2=5,求(4x+2y)2-3x2-y2+2(1-y2)的值.
已知[(x2+y2)-(x-y)2+2y(x-y)]÷4y=1,求4x/4x2-4y2-1/2x+y的值,
已知:x2+2x+y2-6y+10=0,求x,y的值.
已知:x2+y2-10x-2y+26=0,求x、y的值.
已知x2+y2+2x-6y+10=0,求x+y的值.
已知x-y=5,(x+y)2-49,求X2+y2的值
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
已知x+y=8,xy=12,求x2+y2;(x-y)2的值
已知x2-2x+y2+6y+10=0,求(2x-y)的值
已知x2+y2=20,x2+xy-2y2=2(x+2y),求x+y的值