The Student Room Group

Core 3- Volumes of revolution

The region encolsed by the following curves and the x-axis is rotated through 360degrees about the x-axis. Find the volume of the solid generated.

a) y=(x+1)(x-3)

How do I do this? I've tried multiple times and get the wrong answer each time
Volume = πy2dx \pi \int{y^2}dx But you need limits, which will be at the point of intersection of the curves or the point where the curve crosses the x axis. What are the equations of the curves?
(edited 7 years ago)
As the above poster said.

for the curve you gave intersects the x axis at the points:

-1. -10 and -3,-30.
(edited 7 years ago)

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