
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
Given a function $f(x) = ax^3 - bx + 4$, when $x=2$, the function $f(x)$ has an extremum of $-\frac{4}{3}$.

(1) Find the explicit form of the function.
(2) Determine the extreme point(s) of the function and find the maximum value.

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