
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 $\pi < \alpha < \frac{3}{2}\pi$, $\pi < \beta < \frac{3}{2}\pi$, $\sin \alpha = -\frac{\sqrt{5}}{5}$, $\cos \beta = -\frac{\sqrt{10}}{10}$. Find:  
1. The value of $\alpha - \beta$  
2. The value of $\tan(2\alpha - \beta)$.

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