Aptitude - Logarithm - Discussion
Discussion Forum : Logarithm - General Questions (Q.No. 5)
5.
| If log | a | + | log | b | = log (a + b), then: |
| b | a |
Answer: Option
Explanation:
| log | a | + log | b | = log (a + b) |
| b | a |
 log (a + b) = log |
 |
a | x | b |  |
= log 1. |
| b | a |
So, a + b = 1.
Discussion:
33 comments Page 2 of 4.
Sameer said:
1 decade ago
Here someone wrote: loga+logb = log(a+b).
But how log a/b + log b/a = log (a/b x b/a)?
Why not like this log(a/b + b/a)?
But how log a/b + log b/a = log (a/b x b/a)?
Why not like this log(a/b + b/a)?
Harsh said:
8 years ago
@Siddharth.
You cancelled out (a-b) from both sides, which is not accepted since a-b=0 and division by 0 is undefined?
You cancelled out (a-b) from both sides, which is not accepted since a-b=0 and division by 0 is undefined?
Dilshan fernando said:
1 decade ago
log(a/b)+log(b/a) = log(a+b).
log(a/b*b/a) = log(a+b).
log 1 = log (a+b).
log 1 = 0.
So that a+b = 0.
a = -b.
log(a/b*b/a) = log(a+b).
log 1 = log (a+b).
log 1 = 0.
So that a+b = 0.
a = -b.
Shree said:
1 decade ago
log x = (1/2) log y = (1/5) log z, the value of x4y3z-2 is?
Can anyone clearly explain step by step please?
Can anyone clearly explain step by step please?
Manikantan said:
1 decade ago
log a/b +log b/a = log a - log b + log b - log a = 0.
log (a+b)=0 => a+b =1 *(log 1 =0).
log (a+b)=0 => a+b =1 *(log 1 =0).
Amith said:
9 years ago
log (a + b + c) = log a + log b + log c is true only when a + b + c = a * b * c
Eg: 1, 2, 3.
Eg: 1, 2, 3.
Raghavendra said:
1 decade ago
log(a+b)=log(a/b)+log(b/a)
log(a+b)=l0ga-logb+logb-loga
log(a+b)=0
a+b=10^0
so
a+b=1
log(a+b)=l0ga-logb+logb-loga
log(a+b)=0
a+b=10^0
so
a+b=1
Radhe.. said:
1 decade ago
'+' indicate the multiplication in log.and '-' indicate the division in log....
Vijaylaxmi said:
9 years ago
According to rules of logarithms.
Log (a+b) =loga*logb.
Log (a/b) =loga-logb.
Log (a+b) =loga*logb.
Log (a/b) =loga-logb.
Biswas said:
9 years ago
The, log(2+3) = log(2 * 3) should be same in the question 1(b).
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