I don't understand how to get from this:
$\displaystyle S = 2\pi \int \frac{x^3}{3} \sqrt{1+x^4} dx$ [0,3]
to this:
$\displaystyle
= \frac{\pi}{6} \int (1+x^4)^{1/2}(4x^3) dx$ [0,3]
The only thing I understand really is rewriting the square root.
I don't understand how to get from this:
$\displaystyle S = 2\pi \int \frac{x^3}{3} \sqrt{1+x^4} dx$ [0,3]
to this:
$\displaystyle
= \frac{\pi}{6} \int (1+x^4)^{1/2}(4x^3) dx$ [0,3]
The only thing I understand really is rewriting the square root.