解方程3y+7/y+2+2/2-y=3-（3y/y的平方-4﹚

(3y+7)/(y+2)+2/(2-y)=(3-3y)/(y^2-4)
(3y+7)/(y+2)-2/(y-2)=(3-3y)/(y-2)(y+2)
(3y+7)(y-2)-2(y+2)=3-3y
3y^2+y-14-2y-4=3-3y
3y^2-y-18=3-3y
3y^2+2y-21=0
(3y-7)(y+3)=0
y=7/3或y=-3
经检验y=7/3或y=-3是方程的解