Why is dreaming important for animals?

See diagram.we use washers to get the area and we will be integrating with respect to xouter radius is the  distance between y = e^x and y = -1    inner radius of washer is the distance between y = 1 and y = -1    the area of one cross-section of a washer is    solid lies between x = 0 and x = 2. the volume is    if you need this expanded, then    the question doesn't say to evaluate, so we're done.