Question #8f07d

1 Answer
Mar 27, 2017

V= 36piV=36π

Explanation:

Consider the line:

y= x/4y=x4

For x=12x=12 we have y=3y=3, so we can see that rotating this line around the xx-axis in the interval x in (0,12)x(0,12) generates exactly the solid requested.

The element of volume generated by the cylindrical shell between xx and x+dxx+dx is given by:

dV = pi y^2(x)dx = pix^2/16dxdV=πy2(x)dx=πx216dx

so, integrating over the interval:

V= pi/16 int_0^12 x^2dx = pi/16 [x^3/3]_0^12 = 36piV=π16120x2dx=π16[x33]120=36π