If log a + log b = log(a + b), then which relation holds true?
Aptitude
Logarithm
Difficulty: Easy
Choose an option
-
Aab = a + b
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Ba = b
-
Ca/b = b/a
-
Da^b = b^a
Answer
Correct Answer: ab = a + b
Explanation
Given data
- log a + log b = log(a + b)
Concept / Approach
- Use logarithm property: log x + log y = log(xy), for positive x, y (same base).
Step-by-step calculation
log a + log b = log(ab)Given this equals log(a + b)Therefore, ab = a + b (since logarithm is injective on positive reals)ab = a + b
Verification / Notes
Example: a = 2, b = 2 ⇒ ab = 4 and a + b = 4; equality holds and logs match.
Common pitfalls
- Assuming any base or negative values; logs require positive arguments and fixed base.
Final Answer
ab = a + b