
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
Let $(2x+1)^3 = a_0x^3 + a_1x^2 + a_2x + a_3$, which is an identity in $x$ (i.e., it holds for any $x$). Then, the value of $a_1 + a_3$ is \_\_\_\_\_\_.

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