4. Let f(x) = e- and Da = {(x, y) : 0

4. Let f (x) = and Find the volume of the solid obtained by rotating Da about the y-axis. Hence conclude that the volume of the infinite object obtained by rotating Dm around the y-axis is finite. [10 marks] 4. Let f (x) = and Find the volume of the solid obtained by rotating Da about the y-axis. Hence conclude that the volume of the infinite object obtained by rotating Dm around the y-axis is finite. [10 marks]