(4 points) For the function f(x) = 8x + 7 sin(x), find all intervals where the function is increasing. f is increasing on (Give your answer as an interval or a list of intervals, e.g., (- infinity,8] or (1,5),(7,10) . Enter none if there are no such intervals.) Similarly, find all intervals where the function is decreasing: f is decreasing on (Give your answer as an interval or a list of intervals, e.g., (- infinity,8] or (1,5),(7,10) . Enter none if there are no such intervals.) Finally, find all critical points in the graph of f(x) (enter x values as a comma-separated list, or none if there are no critical points)