Calculus

[fly_marlin]

Not sure if you figured it out yet, but graphing the equations along with the axis of revolution helps. You do have to determine the limits of integration algebraically, but looking at the graph will help. Hint: these are generally where the given curve and axis of revolution intersect. The radius of any given section will be given by determining the difference (distance) from the curve to the axis of revolution, thus giving you r (radius), which you plug in to pi*r^2. Then you integrate that within the limits of integration. The key is understanding what the radius is and figuring out where to start integrating and where to end. Hope this helps.

 

[adulbrich 5,000+ posts]

No I haven't figured it out yet, lol.

I'm not going to work on it anymore though. I'm leaving for vacation today

 

[adulbrich 5,000+ posts]

Well, the test is tomorrow. I understand most of the stuff, but sideways parabolas/root functions rotating up with space in between confuses me //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[fly_marlin]

Well, the test is tomorrow. I understand most of the stuff, but sideways parabolas/root functions rotating up with space in between confuses me //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Just make sure you can identify the axis of rotation. If there is a whole in the middle of solid of revolution, simply make sure your radius is from the inner edge to the other edge. Identifying the limits of integration is also important. Also, be sure you understand which variable you're differentiating with respect to. If you can visualize (graphing helps a lot) the curve and all the bounds, you can quickly solve for or identify all the needed info:

1. Limits of integration.

2. Radius of the solid of revolution.

3. Variable you're integrating with respect to.

 

[adulbrich 5,000+ posts]

Just make sure you can identify the axis of rotation. If there is a whole in the middle of solid of revolution, simply make sure your radius is from the inner edge to the other edge. Identifying the limits of integration is also important. Also, be sure you understand which variable you're differentiating with respect to. If you can visualize (graphing helps a lot) the curve and all the bounds, you can quickly solve for or identify all the needed info:
1. Limits of integration.

2. Radius of the solid of revolution.

3. Variable you're integrating with respect to.

Yeah, I get the basic principles, but my teacher makes tricky problems for tests //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[fly_marlin]

If you can graph it, graph it. It's cake from there.

 

[legendndisguise 10+ year member]

I had to go back to Pre-Calc since it's been so long for me in school. Math online is not fun.

 

[adulbrich 5,000+ posts]

If you can graph it, graph it. It's cake from there.

Yeah I can graph it, but the sideways ones I have to graph by hand and they're a pain

I had to go back to Pre-Calc since it's been so long for me in school. Math online is not fun.

I took a math class that was a majority online and loved it! It was MathXL