My Math Forum  

Go Back   My Math Forum > College Math Forum > Calculus

Calculus Calculus Math Forum

LinkBack Thread Tools Display Modes
November 6th, 2013, 09:14 AM   #1
Joined: Oct 2013

Posts: 17
Thanks: 0

Finding Critical Numbers

Hello I got a question for finding critical numbers in a curve sketch.

Find all critical numbers:


I know that f'(x)(10x^9-7x^10)e^-7x

But im not sure what to do next..

Thanks in advance!
SamFe is offline  
November 6th, 2013, 10:14 AM   #2
Senior Member
jks's Avatar
Joined: Jul 2012
From: DFW Area

Posts: 642
Thanks: 99

Math Focus: Electrical Engineering Applications
Re: Finding Critical Numbers

Hi SamFe,

Factor out x^9.
jks is offline  
November 6th, 2013, 12:11 PM   #3
Math Team
Joined: Sep 2007

Posts: 2,409
Thanks: 6

Re: Finding Critical Numbers

I presume you know, although you did not say it, that "critical numbers" for a function are values of x at which f'(x)= 0 or the derivative does not exist.

Yes, if , then .

You should also know that can never be 0 so we must have

Surely solving that is not so difficult! One method is, as jks said, is to factor out : .
Of course, if the product of two numbers is 0, one or the other must be 0.

Another way to do it is to write it as . If , you can divide both sides by .
HallsofIvy is offline  

  My Math Forum > College Math Forum > Calculus

critical, finding, numbers

« integral | find »

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Critical numbers jkh1919 Calculus 10 July 24th, 2012 09:46 PM
Critical Numbers lovetolearn Calculus 1 April 5th, 2012 08:44 PM
First Deriv test, finding critical numbers of this.Need help steelcurtain11 Calculus 2 November 1st, 2011 07:51 PM
Critical Numbers Calc12 Calculus 9 December 14th, 2010 09:18 PM
Critical Numbers lovetolearn Algebra 0 December 31st, 1969 04:00 PM

Copyright © 2019 My Math Forum. All rights reserved.