| Interval | Sign of f\(^\prime\) | Conclusion |
|---|---|---|
| \(( -\infty ,-3)\) | positive | \(f\) is increasing on the interval \(( -\infty ,-3)\) |
| \((-3,1)\) | negative | \(f\) is decreasing on the interval \(( -3,1)\) |
| \((1,\infty )\) | positive | \(f\) is increasing on the interval \( (1,\infty )\) |