Determine the intervals on which the function is concave up or down. 4 ^-1 +5 t w(t) = (Give your answer as an interval in the form (*, *). Use the symbol co for infinity, U for combining intervals, and an appropriate type of parenthesis "(",")", "[","]" depending on whether the interval is open or closed. Enter Ø if the interval is empty. Express numbers in exact form. Use symbolic notation and fractions where needed.) w is concave up on w is concave down on Resources (-∞0,0) U (0,00) Find the point(s) of inflection. (Give your answer as a comma-separated list of points in the form (*, *). Express numbers in exact form. Use symbolic notation and fractions where needed. Enter DNE if the function has no inflection points.)