The function is increasing for:
![(-\infty,-4)\cup(4,\infty)](https://img.qammunity.org/2023/formulas/mathematics/college/3hdtxk04qf50kjw1gt8cmbcvmb8wlt4u3v.png)
And the function is decreasing for:
![(-4,4)](https://img.qammunity.org/2023/formulas/mathematics/college/2wmdzgc40do4f6yvew4zq97qtngdtcqpxv.png)
The local maximum (or minimum) occurs when there may be higher (or lower) points elsewhere but not nearby.
Therefore, the local maximum of the function is:
![(-4,128)](https://img.qammunity.org/2023/formulas/mathematics/college/hb9ohse5u4ijmu6tilrpzc9q04r4u00mkt.png)
And the local minimum of the function is:
![(4,-128)](https://img.qammunity.org/2023/formulas/mathematics/college/z6wz3ormkvpeoipvq75snmc6dxo4qj3cfo.png)