计算:(1)(-7x2-8y2)•(-x2+3y2)=______;(2)(3x-2y)(y-3x)-(2x-y)(3x
计算:(1)(-7x2-8y2)•(-x2+3y2)=______;(2)(3x-2y)(y-3x)-(2x-y)(3x
已知2x+y=7,x2+y2=5,求(4x+2y)2-3x2-y2+2(1-y2)的值.
x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
(x+3y)2+2(x2-y2)(x2+y2)+(x-3y)2.
实数x、y满足3x2+2y2=6x,则x2+y2的最大值为( )
已知(x,y)(x2,y2)在直线y=2x-3上,且x<x2,比较y,y2大小
先化简再求值:-(x2+y2)+[-3xy-(x2-y2)],其中x=-1,y=2.
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
已知实数x.y满足(x2+y2)(x2+y2-1)=2,求x2+y2的值
我做对了吗.x2(x-y)+y2(y-x)= x2(x-y)-y2(x-y)=x2-y2=(x+y)(x-y)
已知x-y+1,X2+Y2=25 求(x+y)2和x2-xy+y2的值
3x2+(-3/2x+1/3y2)(2x-3y)因式分解步骤