My Math Forum  

Go Back   My Math Forum > College Math Forum > Calculus

Calculus Calculus Math Forum


Thanks Tree3Thanks
  • 2 Post By MarkFL
  • 1 Post By soroban
Reply
 
LinkBack Thread Tools Display Modes
February 26th, 2015, 11:31 AM   #1
Newbie
 
Joined: Jan 2015
From: West Virginia

Posts: 11
Thanks: 0

Arc Length

f(x) = (x^5/6)+(1/10x^3)

I get that f'(x) = (5x^4/6)-(3/10x^4). But when I square f'(x) Add plug it into the formula I have no idea what to do with the integral.

Thanks.
joshbeldon is offline  
 
February 26th, 2015, 11:49 AM   #2
Senior Member
 
MarkFL's Avatar
 
Joined: Jul 2010
From: St. Augustine, FL., U.S.A.'s oldest city

Posts: 12,211
Thanks: 522

Math Focus: Calculus/ODEs
I take it from your differentiation that the function is:

$\displaystyle f(x)=\frac{x^5}{6}+\frac{1}{10x^3}$

And so we have:

$\displaystyle f'(x)=\frac{5x^4}{6}-\frac{3}{10x^4}$

Hence:

$\displaystyle 1+\left(f'(x)\right)^2=1+\frac{25x^8}{36}-\frac{1}{2}+\frac{9}{100x^8}=\left(\frac{5}{6}x^4+ \frac{3}{10}x^{-4}\right)^2$
Thanks from greg1313 and joshbeldon
MarkFL is offline  
February 26th, 2015, 12:21 PM   #3
Math Team
 
Joined: Dec 2006
From: Lexington, MA

Posts: 3,267
Thanks: 408

Hello, joshbeldon!

Arc-length problems always require a lot of Algebra.
We must be VERY careful!


Quote:













Thanks from joshbeldon
soroban is offline  
February 26th, 2015, 12:58 PM   #4
Newbie
 
Joined: Jan 2015
From: West Virginia

Posts: 11
Thanks: 0

Its seems that I need to work on my reverse FOIL-ing. Thanks a lot!
joshbeldon is offline  
Reply

  My Math Forum > College Math Forum > Calculus

Tags
arc, calculus 2, length



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Arc Length! Jet1045 Calculus 22 September 15th, 2013 10:16 AM
Length of AB Albert.Teng Algebra 14 January 15th, 2013 07:34 AM
find length if angle and length is given... amin7905 Algebra 4 July 19th, 2012 02:08 PM
Arc length? FreaKariDunk Calculus 3 October 7th, 2011 11:15 AM
arc length future_prodegy Calculus 1 April 12th, 2009 07:24 AM





Copyright © 2019 My Math Forum. All rights reserved.