1/XY+1/(X+1)×(y+1)+1/(X+2)(y+2).1/(x+2012)(y+2012)的值为多少
已知1/x-1/y=4,求(2x+xy-2y)/(x-2xy-y)的值
已知x-y=1,y≠0,求{(x+2y)²+(2x+y)(x+4y)-3(x+y)(x-y)}÷y的值.
已知x²-xy=4,y²-xy=9求下面代数式的值(1)x²-2xy+y²;(2
已知|3-y|+|x+y|=0,求[2(x+y)-3(xy+4)]÷1/xy的值.
已知x,y为实数,且x⒉+1/2y⒉+4≤xy+2y,求x,y的值?
已知x(x+1)-(x²+y)=3,求2分之x²+y²-xy的值
已知x(x+1)-(x²+y)=-3,求(x²+y²)÷2-xy的值
(x+2y-3xy)-(-2x-y+xy),其中x+y=,xy=-,求值.
计算:(1)2/(x+y)+4y/x²-y²(2)x²/x+y-x+y
已知1/x-1/y=3,则代数式(2x-14xy-2y)/(x-2xy-y)的值为多少?
1.已知X+Y=-4,XY=-12,求(Y+1/X+1)+(X+1/Y+1)的值
已知x+y=5,xy=3 (1)x²+y²的值 (2)求x-y(x>y)的值