
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
There is a thin rod with a non-uniform mass distribution. It is known that its linear density is $\rho(x) = 2x$ (taking the line where the rod is located as the $x$-axis, and one end of the rod as the origin). The length of the rod is $l$. Try to express the mass $m$ of the rod using a definite integral, and calculate the value of $m$.

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