Question

difference between disc and washer method to find volume...please give some examples too

Answer 1

Have you tried Paul's Online Notes? Disc/Ring Method: http://tutorial.math.lamar.edu/Problems/CalcI/VolumeWithRings.aspx and Shell/Cylinder Method: http://tutorial.math.lamar.edu/Problems/CalcI/VolumeWithCylinder.aspx . There are many examples to view, with steps and pictures drawn better than I can post here.

Answer 2

Let's take the region bounded by the curve \(y=\sqrt{x+1},~y=0,~x=-1,~x=3\). First we'll revolve this region about the x-axis (\(y=0\)).