Solid formed after revolving the area between #y = x^2# and #y = x+2# around #y# axis?

Two functions
#y=x^2# and #y=x+2#
Around y axis

It will be #(16π)/3# because there is a solid inside other or we have to considerer solid 1 plus solid 2
#(5π)/6 + (16π)/3 = (37π)/6#

1 Answer
Aug 6, 2018

graph{(y-x^2)(y-x-2)=0 [-7.37, 10.41, -1.955, 6.934]}

Ignore the #x^2 le y le x+2# in Q2 as it will be within the solid created by revolving the part in Q1 about the y axis

That leaves:

#underbrace( pi int_0^4 x^2 \ bb(dy) )\_("Volume inside Parabola")- underbrace( pi r^2 h/3)_("Volume of Cone")#

With #y = x^2 qquad \ dy = 2 x dx#

#= 4pi int_0^2 x^3 \ bb(dx) - underbrace( pi * 2^2 * 2/3)_("Volume of Cone")#

#= pi [x^4 ]_0^2 - pi * 2^2 * 2/3 #

#= 40/3 pi#