x(x-1)-(x^2-y)=-4,求2分之x^2+y^2-xy的值

求值域 1,y=(x+2)/(x*x+3x+6) 2,y=3x/(x*x+4) 求y=(5x-1)/(4x+2) (x 已知:【(x²+y²)-(x-y)²+2y(x-y)】/4y=1,求4x/4x²-y²-1/2x+y 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 1.(x-2y)(x+2y)-(x平方+y)(x平方-y) 2.(2x-y)(y+2x)-(2y+x)(2y-x)3.已知：x+y=6,x平方-y平方=48,求x,y的值4.x平方-2x分之x+2 -- x平方-4x+4分之x-1 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 x²-4x-1=0,求(2x-3)²-(x+y)(x-y)-y² x+2y=2x+y+1=7x-y 求：2x-y? 如果|X|=4 |Y|=2 且|X+Y|=X+Y 求X+Y (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 若x*x+y*y=x+y-1/2,求x,y的值如题 x+y=1,xy=-1/2,求x(x+y)(x-y)-x(x+y)2 y=(2x*x-2x+3)/(x*x-x+1),求值域? 已知y = |2x-6| + |x-1| - 4|x+1| ,求y已知y = |2x-6| + |x-1| - 4|x+1| ,求y的最大值 若x.y满足x+=4和x-y=2,求xy分之2x-y+1除以-x分之y+y分之x的值 已知 x-2y=-2 求(2y-x)平方-2x+4y-1