Flipping through Schaum Calculus I stumbled in a problem (the third of chapter 36) that is wrong:
The solution is obscure and this error doesn't look a typo. I'm trying to understand what happened here. Steps are strange and anyway surely something went wrong because the correct solution is $\frac{\pi \left( 28 - 9 \ln(3) - \ln^2(3) \right)}{4}$.
The formula is wrong. When a curve is rotated about the y-axis, the area of the resulting surface of revolution is given by $S = \int^{d}_{c} 2 \pi x \sqrt{1 + (\frac{dx}{dy})^2} dy$.