当x=-1,y=-2时,求代数式[2x2-(x+y)(x-y)][(-x-y)(-x+y)+2y2]的值.
当x=-1,y=-2时,求代数式[2x2-(x+y)(x-y)][(-x-y)(-x+y)+2y2]的值.
已知2x=y,求代数式[(x2+y2)-(x-y)2+2y(x-y)]÷(4y)的值.
当x=2,y=-1时,求代数式(x+y)(x-y)+(x-y)²-(x²-3xy)的值
若|x+y-1|+(x-y-2)²=0,求代数式(x+2y)(x-2y)-(2x-y)(-y-2x)的值.
已知x(x+1)-(x2-y)=-3,求代数式[(x-2y)2+(x-2y)(x+2y)-2x(2x-y)]÷2x的值.
已知x-y+1,X2+Y2=25 求(x+y)2和x2-xy+y2的值
已知x和y满足2x+3y=5,则当x=4时,代数式3x2+12xy+y2的值是( )
已知x2-4x-1=0,求代数式(2x-3)2-(x+y)(x-y)-y2的值
当x+y/x-y=1/2时,求代数式x-y/x+y-2x+2y/x-y的值
已知 x2+xy=12,xy+y2=15,求代数式(x+y)2-2y(x+y)的值.
已知x=3分之1,y=二分之一,求代数式x-(x+y)+(x+2y)-(x+3y)+...-(x+13y)的值
已知y=y1+y2,且y1与x2成反比例,y2与(x+2)成正比例,当x=1时,y=9;当x=-1时,y=5.求y与x之