Use the Shell method to set up and evaluate an integral that gives the volume of the solid generated by revolving the plane region about the y-axis. y= 81-x, y=0 (a) v =4x x(81-x )dx = 65617 Ob) v = 2x x(81-x7 ) dix = 6561 - F 2 O cv=2x x(81-x ) dx = 6561 - FE 2 O d) v = 4x x(81-x )dx= 65617 Oev=2x x(81-x' )dx= 65617