F'(x)=0 x= 1/2 or x =-1/a.

1)1/2 =-1/a means a=-2 f'(x) constant >; =0 At this time, f(x) increases at (0, positive infinity).

2)- 1/a & lt； 0 is a>0 f(x) that increases at (0, 1/2) and decreases at (1/2, positive infinity).

3)a=0 f(x) increases at (0, 1/2) and decreases at (1/2, positive infinity).

4)0 & lt； - 1/a & lt； 1/2 is a.

5)- 1/a & gt； 1/2 is -2

Conclusion: After derivation, we can discuss two solutions by cross multiplication and factorization.

We can consider whether the two are equal, whether they are both within the definition domain (one of them is within the definition domain and does not need to be discussed, and the other should also be considered), and whether there are two specific sizes.

Don't be afraid of trouble in derivative problems. Step by step, you can get a few points.