
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 that -2, $a_1$, $a_2$, -8 are four real numbers forming an arithmetic sequence, and -2, $b_1$, $b_2$, $b_3$, -8 are five real numbers forming a geometric sequence, determine the value of $b_2(a_2-a_1)$.

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