Transcript
A problem in calculus called Surface Area of a Revolution. So let’s do it. Index 8 to get to my menu. We’re going to go up to get to the bottom of the alphabet. And scroll up to Surface Area of Revolution.
We’re going to enter our, I’ll show you the actual formula here. Let’s write down your paper first. Press Alpha to enter anything into these entry lines here. Alpha x cubed over the range of alpa zero for a for b, Alpha 2. I show you what you’ve entered so you can change it if you want. I say it’s okay. The first derivative is 3x squared. That goes into the formula here. That’s part of the formula. Over 0 and 2 for the range. And we start doing the computations. Squaring things. This is U Substitution. U equals this. DU equals 36. You always take 36 and put it on the other side as a denominator. DU/36 equals that. And this x cubed equals the problem. X cubed dx. And then we substitute for U. In the problem here, DU 36 has to come out of the integral. So that 2 pi, there’s the 1 over 36 here and that computes to pi over 18, etc. We’re doing the integral of one half, of course you add two halves to that and Upper Range less than the Lower Range. And you get 203 squared units. Pretty neat, huh? everystepcalculus.com. Go to my site, subscribe to see more videos or go to the menu and look up what you need to learn about and pass your calculus. Have a good one.
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