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If log a + log b = log(a + b), then which relation holds true?

Difficulty: Easy

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

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