
Yefim S. answered 04/28/20
Math Tutor with Experience
Intersection of curves y = lnx and y = 1 give us equation lnx = 1, or x = e;
Becouse 1 ≤ x ≤ e, external radius R = 1 - (- 1) = 2 and inner radius of rotation r = lnx - (- 1) = lnx + 1;
so volume V = π∫1e[22 - (lnx + 1)2]dx = π∫1e(3 - ln2x - 2lnx)dx;
Sorry, but I can't make picture with this editor..