+0  
 
+13
85
7
avatar+1074 

Find  when

 Mar 14, 2020
 #1
avatar+20885 
+1

        2log(a - 2b)  =  log(a) + log(b)

        log(a - 2b)2  =  log(ab)

             (a - 2b)2  =  ab

    a2 - 4ab + 4b2  =  ab

     a2 - 5ab + 4b2  =  0

      (a - 4b)(a - b)  =  0

 Either  a = 4b   or   a = b                                  (It is impossible for a to equal b)

 

--->   a/b  =  1/4  

 Mar 14, 2020
 #2
avatar+1074 
+8

Sorry, but 1/4 is incorrect.

 Mar 14, 2020
 #3
avatar+109509 
0

Why do you think so?

Geno justified his answer - you should justify your response.

Melody  Mar 15, 2020
 #4
avatar+1074 
+9

I tried that answer, and it was incorrect.

SpongeBobRules24  Mar 15, 2020
edited by SpongeBobRules24  Mar 15, 2020
 #5
avatar+30038 
+2

Geno made a slight slipup in the last line. He went from a = 4b to a/b = 1/4 instead of a/b = 4. If you had followed his reasoning instead of just looking at the final answer you might have spotted this!

Alan  Mar 15, 2020
 #6
avatar+1074 
+9

I looked over his answer, and it is very easy to mix up the final answer. I have made that mistake on similar problems in the past, where I thought the answer was 1/5, but it was 5.

SpongeBobRules24  Mar 15, 2020
edited by SpongeBobRules24  Mar 15, 2020
edited by SpongeBobRules24  Mar 15, 2020
edited by SpongeBobRules24  Mar 15, 2020
 #7
avatar+109509 
-1

If you had studied Gino's answer, understood it

Then done it yourself without looking at his.

 

 

You would have found the trivial error for yourself. 

Melody  Mar 16, 2020

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