1- Determine the open intervals on which the graph is concave upward or concave downward.

f(x) = 4/ x^2 + 2

2- Apply the first derivative test to find the intervals on which f(x)= x^2 - 2x +1/ x+1 is increasing and/or decreasing

3-Suppose that the price p (in dollars) and the weekly sales x (in thousands of units) of a commodity satisfy the demand equation 2p + x ² = 1500.How fast are the sales changing at a time when x = 4, p = 9 and the price is rising at the rate of $3 per week?