MY NOTES Consider the following function. g(x) = x + 8x + 6 Find the first and second derivatives of the function. g'(x) = -2x+8 g"(x) = -2 Determine where the function is concave upward and where it is concave downward. (Enter your answer using interval notation. If an answer does not exist, enter DNE.) concave upward DNE concave downward (-2,)