设6x^2-5xy-4y^2-11x+22y+m=（3x+ay+b)(2x+cy+d)
对右边展开
（3x+ay+b)(2x+cy+d)=6x^2+3cxy+3dx+2axy+acy^2+ady+2bx+bcy+bd
=6x^2+(2a+3c)xy+acy^2+(2b+3d)x+(ad+bc)y+bd
于是 2a+3c=-5,ac=-4
解得 a= -4 c=1
∵1/x-1/y=3
∴y-x=3xy
x-y=-3xy
2x+3xy-2y/x-2xy-y
=[2(x-y)+3xy]/[(x-y)-2xy]
=(-6xy+3xy)/(-3xy-2xy)
=-3xy/(-5xy)
=3/5那那两道因式分解怎么做啊,,3）因式分2x^2+9x-5x^2-2x-6 =2x^2-5x^2+9x-2x-6 =-3x^2+4x-6 =（x-2）（-3x+3） 6x^2-3y^2-7xy=(2x-3y)(3x+y)