I am unsure how to solve these problems.

Find the relative maxima and relative minima, if any, of the function. (If an answer does not exist, enter DNE.) f(x) = 3x4 - 4X3 + 7 relative maximum (x, y) = relative minimum ( x, y) =Air Pollution According to an Air Quality Management District, the level of nitrogen dioxide, a brown gas that impairs breathing, present in the atmosphere on a certain May day in a busy downtown city is approximated by A(t) = 0.03t3(t 7)4 + 68.0 (o s t s 7) where A(t) is measured in pollutant standard index (PSI) and t is measured in hours, with t = 0 corresponding to 7 am. At what time of day is the air pollution increasing, and at what time is it decreasing? (Enter your answers using interval notation in terms of t.) increasing decreasing