Question

find the interval(s) where the function is increasing and the interval(s) where it is decreasing. (enter your answers using interval notation. if an answer does not exist, enter dne.)

Answer 1

We need to take the derivative, which is:

`f'(x) = 10x + 2`

and see where it is positive (increasing) and negative (decreasing). We see that
`f'(x) = 0 at x = -1/5, f'(x) < 0 for x < -1/5, and f'(x) > 0 for x > -1/5`. Therefore, we have

f(x) increasing: (-1/5, ∞)

f(x) decreasing: (-∞, -1/5)