
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
Simplify and evaluate the expression: $a(a^4 - a + 1)(a - 2)$, where $a = -\frac{1}{2}$. Also, simplify the expression: $(x + 2y)(x - y) - (2x - y)(-x - y)$, where $x = 8$ and $y = 5$.

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