Aptitude - Logarithm - Discussion

Discussion Forum : Logarithm - General Questions (Q.No. 1)
1.
Which of the following statements is not correct?
log10 10 = 1
log (2 + 3) = log (2 x 3)
log10 1 = 0
log (1 + 2 + 3) = log 1 + log 2 + log 3
Answer: Option
Explanation:

(a) Since loga a = 1, so log10 10 = 1.

(b) log (2 + 3) = log 5 and log (2 x 3) = log 6 = log 2 + log 3

      log (2 + 3) log (2 x 3)

(c) Since loga 1 = 0, so log10 1 = 0.

(d) log (1 + 2 + 3) = log 6 = log (1 x 2 x 3) = log 1 + log 2 + log 3.

So, (b) is incorrect.

Discussion:
38 comments Page 4 of 4.

Suhaas said:   10 years ago
@Palak Kapoor.

The answer is undefined.

log{5 - 4}[5^2 - 4^2 - 4]
log{1}[25 - 16 - 16]
log[25 - 32]
log[- 7]
log value for -ve is undefined.

SYLVESTER said:   10 years ago
The given answer is absolutely correct.

Meenakshi said:   10 years ago
The anwer is absolutely correct according to log properties.

It's log a + log b = log(a * b).
not log(a + b) = log(ab).

RAVI said:   9 years ago
@all.

B is absolutely correct.

Disha jhan said:   9 years ago
The answer B is correct. I agree with it.

Isaac said:   9 years ago
Can someone help me understand how D is a true statement?

If log6=10^6=1,000,000
how is that equal to log1+log2+log3?
=10^1+10^2+10^3,
=10+100+1000,
=1110.

Sanyal said:   9 years ago
Correct, Thanks for the given explanation.

K.manohar reddy said:   1 decade ago
Its absolutely correct.


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