(x2+xy+y2)(x2+xy+2y2)-12y4.
已知x2+4y2+x2y2-6xy+1=0,求 x4-y4/2x-y 乘 2xy-y2/xy-y2 除以(x2+y2/x
(2x2-3xy+4y2)+(x2+2xy-3y2)化简(要有过程)
已知:x2+y2=4xy,求(x4+y4)÷(xy)2
在x2+2xy-y2,-x2-y2+2xy,x2+xy+y2,4x2+1+4x中,能用完全平方公式分解因式的有( )个
因式分解:x2-2xy+y2-z2.
已知x2+xy=2,y2+xy=5,则12x2+xy+12y2=___.
已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2的值为( )
已知x2-xy=21,xy-y2=-12,分别求式子x2-y2与x2-2xy+y2的值.
如果M=3x2-2xy-4y2,N=4x2+5xy-y2,则8x2-13xy-15y2等于( )
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
先化简再求值:-(x2+y2)+[-3xy-(x2-y2)],其中x=-1,y=2.