+0  
 
0
939
5
avatar
2log25 - 3log5 + log20 = ?
Guest Sep 28, 2014

Best Answer 

 #3
avatar+93299 
+10

Great work anon.    

I'm just going to look at it a slightly different way. 

$$\\2log25 - 3log5 + log20 \\
=2log5^2-3log5+log4+log5\\
=4log5-3log5+log2^2+log5\\
=2log5+2log2\\
=log25+log4\\
=log100\\
=log10^2\\
=2log10\\
=2*1\\
=2$$

 

You beat me Alan.   

Melody  Sep 28, 2014
 #1
avatar
+8

2log25 - 3log5 + log20 =

2 log (5*5) -3 log 5 + log (2*2*5)

 

We know that: log (a*b)= log a + log b:

 

2 (log 5 + log 5) -3 log 5 + log 2 + log 2 + log 5=

4 log 5 - 3 log 5 +log 5 + 2 log 2=

2 log 5 + 2 log 2

Guest Sep 28, 2014
 #2
avatar+26971 
+10

You can take it just a little further Anonymous:

2log(5) + 2log(2) = log(52) + log(22) = log(25) + log(4) = log(25*4) = log(100) = 2 (assuming log to the base ten)

Alan  Sep 28, 2014
 #3
avatar+93299 
+10
Best Answer

Great work anon.    

I'm just going to look at it a slightly different way. 

$$\\2log25 - 3log5 + log20 \\
=2log5^2-3log5+log4+log5\\
=4log5-3log5+log2^2+log5\\
=2log5+2log2\\
=log25+log4\\
=log100\\
=log10^2\\
=2log10\\
=2*1\\
=2$$

 

You beat me Alan.   

Melody  Sep 28, 2014
 #4
avatar+88830 
+5

We have

2log25 - 3log5 + log20

2log(5*5) - 3log 5 + log (4*5)

2log 5 + 2log 5 - 3log 5 + log4 + log 5      combine like terms

5log5 - 3log 5 + log4 =

2log5 + log 4 =

log52 + log 4 =

log 25 + log 4 =

log (25*4) =

log 100 =

2

 

CPhill  Sep 28, 2014
 #5
avatar+88830 
+5

We have confirmed it ......the answer is   2 !!!!!!!

 

CPhill  Sep 28, 2014

31 Online Users

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.