
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
The function $f(x)=\begin{cases} -x-3a & (x < 0) \\ a^{x}-2 & (x\geqslant 0) \end{cases}$, where $(a > 0$ and $a\ne 1)$, is a decreasing function on $\mathbb{R}$. The range of values for $a$ is \_\_\_\_.

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