
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
If the function $f(x)=ax^{2}+2x- \dfrac {4}{3}\ln x$ attains an extremum at $x=1$.
$(1)$ Find the value of $a$;
$(2)$ Determine the intervals of monotonicity and the extremum of the function $f(x)$.

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