+0

+13
85
7
+1074

Find  when

Mar 14, 2020

#1
+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
+1074
+8

Sorry, but 1/4 is incorrect.

Mar 14, 2020
#3
+109509
0

Why do you think so?

Melody  Mar 15, 2020
#4
+1074
+9

I tried that answer, and it was incorrect.

SpongeBobRules24  Mar 15, 2020
edited by SpongeBobRules24  Mar 15, 2020
#5
+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
+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
+109509
-1