Help me pls

(5 points) Let f(x) = etz + e-3z. Find the intervals on which f is increasing or decreasing. Enter your answer as an interval or union of intervals. Use a capital letter 'U' for union. Enter "{ }" if the function is never increasing or decreasing. Increasing: Decreasing: List the x-values of any local extrema, separated by commas. Enter 'N' if there are none. Local maxima: Local minima: Find the intervals on which f is concave up or concave down. Enter "{ }" if the function is never concave up or concave down. Concave Up: Concave Down: List the ar-values of any points of inflection, separated by commas. Enter 'N' if there are none. Points of inflection