First, find the roots .
Hi,
If y= 4x^3+3x^2-4x-3, calculate the volume of the body obtained by rotating y around 1) the x axis 2) the y axis.
I'm at a bit of a loss here. I know the formula for rotating about the x axis is the integral of pi.y^2 and integral of pi.x^2 for rotation about the y axis.
For the x axis rotation, i presume I have to square out the whole function and then integrate bit by bit. However, for rotation about the y axis, how do I express x^2 in terms of y? Bit confused, would appreciate help!
Sorry, Just realised , can I use the shell method for rotating about the y axis? i.e that the volume of a solid rotated about the y axis can be written as the integral of 2pixf(x) between the limits a and b?