My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Thanks Tree4Thanks
  • 1 Post By Choboy11
  • 3 Post By JeffM1
Reply
 
LinkBack Thread Tools Display Modes
July 8th, 2017, 01:24 PM   #1
Newbie
 
Joined: Jul 2017
From: United Kingdom

Posts: 4
Thanks: 0

Math Focus: General
Smile Logs

I have a little problem with Logs.

(log(3x)+log(9x^2))/3

I worked it out to be Log(27x) but it can be simplified further down to Log(3x)

Can anybody help me figure out how?

Thanks!

JayWalk is offline  
 
July 8th, 2017, 01:53 PM   #2
Newbie
 
Joined: May 2017
From: California

Posts: 11
Thanks: 1

Try to use log(3x) + log(9x^2) = log(3x*(9x^2))

then use log(x) * a = log(x^a).. so log(x) / a = log(x^(1/a))
Thanks from JayWalk
Choboy11 is offline  
July 8th, 2017, 02:29 PM   #3
Senior Member
 
Joined: May 2016
From: USA

Posts: 785
Thanks: 311

Quote:
Originally Posted by JayWalk View Post
I have a little problem with Logs.

(log(3x)+log(9x^2))/3

I worked it out to be Log(27x) but it can be simplified further down to Log(3x)

Can anybody help me figure out how?

Thanks!

$\dfrac{\log(3x) + \log(9x^2)}{3} = \dfrac{\log(3x) + \log(\{3x\}^2)}{3} =$

$\dfrac{\log(3x) + 2\log(3x)}{3} = \dfrac{3\log(3x)}{3} = \log(3x).$

EDIT: This is just a different way from in the previous post.

$\dfrac{\log(3x) + \log(9x^2)}{3} = \dfrac{\log(3x * 9x^2)}{3} = \dfrac{\log(27x^3)}{3}.$

Now you can go

$\dfrac{\log(27x^3)}{3} = \dfrac{\log(\{3x\}^3)}{3} =$

$\dfrac{3\log(3x)}{3} = \log(3x).$

Or you can go:

$\dfrac{\log(27x^3)}{3} = \dfrac{1}{3} * \log(27x^3) =$

$\log(\{27x^3\}^{(1/3)}) = \log \left ( \sqrt[3]{27x^3} \right ) = \log(3x).$

Lots of ways to proceed.
Thanks from topsquark, Choboy11 and JayWalk

Last edited by skipjack; July 8th, 2017 at 09:14 PM.
JeffM1 is offline  
July 8th, 2017, 05:23 PM   #4
Newbie
 
Joined: Jul 2017
From: United Kingdom

Posts: 4
Thanks: 0

Math Focus: General
I can't believe I didn't see it at first.

Thanks!

JayWalk is offline  
Reply

  My Math Forum > High School Math Forum > Algebra

Tags
logs



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Having some problems understanding logs (natural logs) leo255 Algebra 4 January 26th, 2014 08:49 AM
Logs Help Lewan Algebra 3 May 7th, 2013 12:13 PM
logs milanstar Algebra 3 May 12th, 2012 12:13 PM
Help on solving problems with logs and natural logs! rokr32 Algebra 1 February 1st, 2012 03:13 PM
logs milanstar Calculus 0 December 31st, 1969 04:00 PM





Copyright © 2017 My Math Forum. All rights reserved.