important note I need the answer with an explanation

Q2) a) Let f(x) = x *,x > 0. Find the interval on which f is increasing or decreasing, and find the local maximum and minimum, if any. b) A square sheet of cardboard with each side a centimeters is to be used to make an open-top box by cutting a small square of cardboard from each of the corners and bending up the sides. What is the side length of the small squares if the box is to have as large a volume as possible