
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 sets $A=\{x|x^2-x-12\leq0\}$, $B=\{x|m+1\leq x\leq 2m-1\}$,  
(1) When $m=3$, find the set $A\cup B$;  
(2) If $A\cup B=A$, find the range of $m$.

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