Answer:
<em>A=3 and B=6</em>
Step-by-step explanation:
<u>Increasing and Decreasing Intervals of Functions</u>
Given f(x) as a real function and f'(x) its first derivative.
If f'(a)>0 the function is increasing in x=a
If f'(a)<0 the function is decreasing in x=a
If f'(a)=0 the function has a critical point in x=a
As we can see, the critical points may define open intervals where the function has different behaviors.
We have
Computing the first derivative:
We find the critical points equating f'(x) to zero
Simplifying by -6
We get the critical points
They define the following intervals
Thus A=3 and B=6