若2x+y=6 xy=2.5 求2x—y等于多少

若2x+y=6 xy=2.5 求2x—y等于多少 若x^2+xy+y=14,y^2+xy+x=28,求x+y 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y 若x+y=5,xy=6,求x^2y+xy^2的值 若正实数x,y满足2x+y+6=xy,求xy的最小值. 若正实数X,Y满足2X+Y+6=XY,求XY的最小值. 若x+y=4,x-y=6,求xy(y^2+y)-y^2(xy+2x)-3xy的值. 若x-y=5,xy=6,求x^2-xy^2和x^2y+xy^2 1-2/x+y=xy,4y+6x=xy.求xy的解? 若1/X—1/Y=2,求3X-2XY-3Y/X-2XY-Y 若x+y=4 x-y=6 求xy(x^2+y)-y^2(xy+2x)-3xy的值求值 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 若(y-x)/xy=3,求分式(2x+3xy-2y)/(x-2xy-y)的值 若y-x/xy=3,求分式2x+3xy-2y/x-2xy-y 若x+y-5xy=0,求(2x-3xy+2y)/(x+2xy+y)的值 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 若xy=2（x+y),求 （3x-5xy+3y)÷(-x+3xy-y) 的值