
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
(In 2009) If the function $y = \frac{1}{3}ax^3 - \frac{1}{2}ax^2 - 2ax$ (where $a \neq 0$) is increasing on the interval $[-1, 2]$, then the range of values for the real number $a$ is _______.

Present the answer in LaTex format: \boxed{Your answer}
user