
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 the logarithmic function $f(x)=\log _{a}x (a > 0$ and $a\neq 1)$, and its graph passes through the point $(4,2)$.
(1) Find the value of the real number $a$;
(2) If $f(x+1) < 0$, find the range of the real number $x$.

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