(2×y+x²-y²)-(x²-y²-3xy) 代数的值

(2×y+x²-y²)-(x²-y²-3xy) 代数的值 已知x+y=4.x-y=6.求代数式xy(y²+y)-y²(xy+2x)-3xy的值 已知x/y等于3,求x²+2xy-3y²/x²-xy+y²的值 已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值 已知y/X=3,求x²-xy+y²/x²+2xy-3y²的值 已知x/y=2,求x²-xy+3y²/x²+xy+6y²的值 1/x+1/y=5,求2x-3xy+2y/x²+xy+y的值 已知x-3y=0,求(x²-2xy+y²/x-y)-2y的值 x/y=3,求x²+y²-xy/x²-y²的值. 若正数x,y满足x²-y²=2xy,求（x-y)/(x+y)的值 正数x,y满足x²-y²=2xy,求x-y/x+y的值 求3xy²-4x²y-2xy²+ 5x²y的值,其中x,y满足|x-1|+(y+