
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 an arithmetic sequence $\{a\_n\}$ that satisfies $a\_3 = 7$ and $a\_5 + a\_7 = 26$. Let $S\_n$ denote the sum of the first $n$ terms of the sequence.

(1) Find the expression for $a\_n$ and $S\_n$.

(2) Let $b\_n = \frac{1}{a\_n^2 - 1}$ for all positive integers $n$. Find the sum of the first $n$ terms of the sequence $\{b\_n\}$, denoted by $T\_n$.

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