Applications of Differentiation and Partial Derivatives. Answer the following questions and choose the correct letter. URGENT!!!Thankyou!

Applications of Differentiation and Partial Derivatives $2 Letf(=c)= 32+ . Find the interval(s) on which I is increasing. 2 Let f(a:) = 32:: l . Find the interval(s) on which f is decreasing. z\" $2+1 Let f(2:) = . Find the open interval(s) on which f is concave up. 2' 33+1 Let x) = . Find the open interval(s) on which I is concave down