I am having a bit trouble with a question about rotational
volume. So, this is the problem: "An area R in the xy plane is
given by: 0 ≤ x ≤ 1 0 ≤ y ≤ x3 Find the volume when rotating R
around the axis y = -1" Here is how I was thinking. First, I
drew this figure: My idea was to draw the boundaries, and two
radius in red, which I need to find in order to use the washer
method. So, I thought the lower boundary must be r(y) = g(y) - c
= x3 - (-1) = x3 + 1 (The second red line in the picture) But I
am unsure what I should put as the upper boundary (The first
radius in the picture). I hope someone can help and tell me in
what way I am thinking wrong.