(a^2-9)/(a^2+6a+9)除以（a-3）/(a^2+3a)减去（a-a^2）/(a^2-1)结果是多少?

(a^2-9)/(a^2+6a+9)除以（a-3）/(a^2+3a)减去（a-a^2）/(a^2-1)结果是多少?
(a^2-9)/(a^2+6a+9)除以（a-3）/(a^2+3a)减去（a-a^2）/(a^2-1)结果是多少?

(a^2-9)/(a^2+6a+9)除以（a-3）/(a^2+3a)减去（a-a^2）/(a^2-1)结果是多少?
(a^2+2a)/(a+1)

=(a+3)(a-3)/(a+3)²×a(a+3)/(a-3) +a(a-1)/(a+1)(a-1)
=a +a/(a+1)
=(a²+2a)/(a+1)

(a^2-9)/(a^2+6a+9)除以（a-3）/(a^2+3a)减去（a-a^2）/(a^2-1)
=(a+3)(a-3)/(a+3)²除以（a-3）/a(a+3)减去a（1-a）/(a+1)(a-1)
=(a-3)/(a+3) × a(a+3)/(a-3)+a/(a+1)
=a+a/(a+1)
=(a²+a+a)/(a+1)
=(a²+2a)/(a+1)