
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 $f(x)$ be a differentiable function, and it satisfies $$\lim_{\Delta x \to 0} \frac {f(1+2\Delta x)-f(1)}{\Delta x} = -2,$$ then find the derivative of the function $y=f(x)$ at $x=1$.

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