College algebra

Question

y=f(x)  List the intervals where f is decreasing. (Enter your answer using interval notation.) 

Answer 1

y=f(x)

is increasing when f'(x)>0

it's decreasing when f'(x)<0

It's flat, horizontal when f'(x) = 0

Just take the derivative of f(x) and its sign tells you whether it's increasing or not