12 Consider the rational function f(2) 3x2 + 2.5 f (I) has two inflection points at T C and : - D with C : D. Find the exact values of C and D. For each of the following intervals, determine whether f (I ) is concave up or concave down. (-oo, C): Select an answer v (C, D): Select an answer v (D, co): Select an answer v The graph of f(I) shown below will help you determine whether your answers are reasonable, but you need to use Calculus to determine the exact values. 3- 2 -3 -2 12 3 0