A plain curve is revolved about the line, x = -4, a vertical element dA is used to solve for the volume of the solid generated. Using the cylindrical shell method, the expression for r is O X O x+4 O yhigher " Ylower O x-4 D Question 12 5 pts Which of the following is the integral equivalent of the volume of the solid formed by rotating around y = -1 of the region bounded by 2 + 1 = 1 and y = in the first quadrant using cylindrical shells? of1215 2 7 ( 3 ) (1 - 4 / 1 - ) dy 0 1 12/5 2 7 ( 8 + 1 ) ( 4 / 1 - , - 2) dy 1 1215 2 x ( 3 + 1 ) ( 4 / 1 - , - y) dy 0 1 12/5 2 X ( 31) ( 4 / 1 - 5 - 1 ) dy