# Vol of revolution(1 line and 1 function)

**Calculus**Level pending

Find the volume of the solid of revolution formed by revolving the region bounded by \( f(x)=x+4\) and the \(x\)-axis (\(2\leq x\leq4\)) about \(y\)- axis. If your answer is \( \dfrac ab \pi\)*21/64, where \( a\) and \(b\) are coprime positive integers, find \(a+b\).