
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 function $f(x)=ae^{x}-x$ ($a\in \mathbb{R}$), where $e$ is the base of the natural logarithm, $e=2.71828…$
- (I) Determine the monotonicity of the function $f(x)$ and explain the reason.
- (II) If $x\in[1,2]$, the inequality $f(x)\geqslant e^{-x}$ always holds, find the range of values for $a$.

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