
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 the logarithmic function $y=\log_a(4-x)$, where $a>0$ and $a \neq 1$:
1. Find the domain of the function.
2. Determine the monotonicity of the function directly (without proof).
3. When $a=2$, choose a value of $x$ that you like, and calculate the corresponding function value.

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