
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
When the number of toxic bacteria in a room starts to increase, it is necessary to use a bactericide. At the beginning of its use, the number of bacteria will continue to increase, but as time goes on, the rate of increase gradually decreases, until at a certain point, the number of bacteria begins to decrease. If the number of bacteria $b(t)$ after using the bactericide for $t$ hours is $b(t)=105+104t-103t^2$.

(1) Find the instantaneous speed of the bacteria at $t=5$ and $t=10$; (2) During which period does the number of bacteria increase, and during which period does it decrease? Why?

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