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.
Rajaa said:
1 decade ago
Problem: log(a/b)+log(b/a) = log(a+b).
log(a)+log(b) = log(a*b).
So LHS log(a/b)+log(b/a) = log(a/b*b/a).
= log(1).
And RHS log(a+b).
LHS = RHS.
log(a+b) = log(1).
Hence a+b = 1.
log(a)+log(b) = log(a*b).
So LHS log(a/b)+log(b/a) = log(a/b*b/a).
= log(1).
And RHS log(a+b).
LHS = RHS.
log(a+b) = log(1).
Hence a+b = 1.
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
What is the solution for:
log{(a+b)/3} = 0.5(log a + log b).
The answer is a^2+b^2 = 7ab.
But I want the procedure using the formula as mentioned here please.
log{(a+b)/3} = 0.5(log a + log b).
The answer is a^2+b^2 = 7ab.
But I want the procedure using the formula as mentioned here please.
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?
Ravi said:
10 years ago
Formula for log x to base a.
Can anyone help me?
Can anyone help me?
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.
Siddharth said:
9 years ago
I have a question.
Log a =log b
a = b
a * a = ab
(a * a)- b * b = ab - b *b
(a + b)(a - b) = b(a - b)
a + b = b
But a = b
So
B + b = b
Were is the mistake? Please clarify this.
Log a =log b
a = b
a * a = ab
(a * a)- b * b = ab - b *b
(a + b)(a - b) = b(a - b)
a + b = b
But a = b
So
B + b = b
Were is the mistake? Please clarify this.
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).
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?
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