Final answer:
The intervals of increase and decrease can be found using the first derivative test, the second derivative test, or both. Hence the correct answer is option C
Step-by-step explanation:
a) Use the first derivative test
b) Use the second derivative test
c) Both a and b
d) Neither a nor b
When finding intervals of increase and decrease, you can use the first derivative test, the second derivative test, or both. The first derivative test helps determine where the function is increasing or decreasing by analyzing the sign of the derivative. The second derivative test helps determine the concavity of the function, which can indicate where the function is increasing or decreasing. Therefore, the correct answer is: c) Both a and b.