dominet

Annnd I just answered my own post again: divide the volume into 2 volumes (first from y=0 till y=1, second from y=1 till y=49) then add them. In other words: http://www.wolframal...+dy+from+0+to+1 ++++Plus++++ http://www.wolframal...dy+from+1+to+49

Hello, I'm trying to find the Volume of this solid by the Shell Method but can't figure out what the height of the shell is for this: rotation about x-axis of region bounded by y=x^2 and y=6x+7 the formula should be: Volume= 2pi int(radius*height) dy from 0 to 49. I know radius is y. But what is the height?

I realized the problem was just that I should have used absolute value for the radius. So the answer would be: integral of 2pi*(|-1-x|(6x+7-x^2)).dx from -1 to 7

Hello. My homework requires me to find the volume of a solid by shells but my Math teacher only explained a simple exam with only 1 function revolved about the x-axis or y-axis where the radius is either just "y" or "x". In my homework, I see questions like this: Find Volume by shell method of region bounded by: y=6x+7 and y=x^2 about the line: a) x= -1 b) x= 7 I don't know how to find the radius here. My attempt at "a)" was: integral of 2pi*((-1-x)(6x+7-x^2))*dx from -1 to 7 but that gave me a negative answer. Can someone explain to me how to usually find the radius and height of the shell for questions of this form? Thank you.