X+Y=16 XY=15 X=?,Y=?,求方法、过程、结果

|x|/x+y/|y|+xy/|xy|= 化简:(x+y-4xy/x+y)*(x-y-4xy/x-y)= 证明|xy|=|x||y| xy-(x+y)=1000 证明|xy|=|x||y| xy=15,x+y=8,x,y=? x^2+xy=12,xy+y^2=15,求(x+y)^2-(x+y)(x-y) y'-xy=x/y通解 xy=y'ln(y'/x) 解方程x*x+xy=y+y*y 1/x-1/y=x,求5y+xy-5y/y-xy-x=? f(xy,x-y)=x^2+y^2+xy;f(x,y)/∂x;f(x,y)/∂y xy=(x-15)(y+6) f(x,y)=xy+e^x x arctanx/y ,求f(x+y,x-y) x^+2xy+y^+4=16 x^-2xy+y^=16 求(3xy+6y^)+|x^-(2xy+2y^-3x^)|的值 sin(x*x+y)=xy 求y'x x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________? X+X+Y+Y+Y=56,X+X+X+Y+Y=54.X=?Y=?XY=?