
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]


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Given that $f(x)$ is a differentiable function defined on $(-\infty, 0)$ with its derivative $f'(x)$, and it is known that $3f(x) + xf'(x) > 0$ for $x < 0$, determine the solution set for the inequality $(x+2017)^3f(x+2017) + 27f(-3) > 0$.

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