
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 the sum of the first $n$ terms of the positive sequence $\{a\_n\}$ is $S\_n$, and it satisfies the equation $S\_{n+1}= \frac {1}{2}a_{2}S_{n}+a_{1}$, with $S_{3}=14$.
(I) Find the general term formula of the sequence $\{a\_n\}$.
(II) If $b_{n}=a_{n}-1$, find the value of $\frac {a_{1}}{b_{1}b_{2}}+ \frac {a_{2}}{b_{2}b_{3}}+...+\frac {a_{n}}{b_{n}b_{n+1}}$.

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