I think I'm missing something. This seems relatively easy but I am not getting the right answer.
Find the arc length.
for
Using:
I get:
Then when I evaluate at my limits, I get 7. Which is the wrong answer in Webassign. I also tried it using u-substitution and got like 54 for an answer.
CAn someone get me straight here?
Thanks!!
You are essentially doing the chain rule in reverse. The derivative of the inner function, is just 81, so there needs to be an 81 outside of the radical in order to put the integrand into the form And of course, if we put 81 into the integrand, we will have to divide by 81 somewhere to cancel it out.
If you have trouble "seeing" the patterns, you can go through the process more explicitly by using -substitution (in this case, let ). As you gain a little experience with basic integration, you will find that you no longer need to write out the substitution for the simpler integrals.
I will leave your other post for another member, as I need to be getting to bed. Take care.