(x-y)(x2+xy+y2)
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
已知x-y+1,X2+Y2=25 求(x+y)2和x2-xy+y2的值
已知x2+y2=20,x2+xy-2y2=2(x+2y),求x+y的值
x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
已知x2+y2-10x-6y+34=0,求(x-y/x+y)2÷x2-y2/xy×x2+2xy+y2/x2-xy 的值.
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
先化简再求值:-(x2+y2)+[-3xy-(x2-y2)],其中x=-1,y=2.
先化简再求值2(x2-xy)-3(2x2-3xy)-2[x2-(2x2-xy+y2)],其中x=-1,y=-2.
先化简,再求值:2x2+(-x2-2xy+2y2)-3(x2-xy+2y2),其中x=2,y=-12
分解因式:8(x2-2y2)-x(7x+y)+xy.
满足方程x2+y2=2(x+y)+xy的所有正整数解有( )