Skip to content

Geometric Progression With Logarithms

Hardmathematics

If positive numbers x, y, z are in geometric progression, then the logarithms log x, log y, log z to a common base form which kind of progression?

Select the correct option:

🔒 Solution Hidden from View

Submit your answer to unlock the detailed step-by-step solution.

About This Question

Subject
mathematics
Chapter
sequence and series
Topic
geometric progression with logarithms
Difficulty
Hard
Year
2025
Tags
advanced-calculus-drillgeometric-progressionlogarithmarithmetic-progressiontransformation

Solution

Correct Answer:

Arithmetic progression

This question links progressions through the logarithm's transformation of products into sums, a connection JEE Advanced uses to convert multiplicative structure into additive structure. Since x, y, z are in GP, the middle term satisfies y^2 = xz. Taking logarithms of both sides gives 2 log y = log x + log z, which is precisely the defining condition for log x, log y, log z to be in arithmetic progression. Thus the logarithms form an AP. Option geometric progression is wrong because logarithms convert the constant ratio into a constant difference, not a ratio. Option harmonic progression has no basis here, since reciprocals of logarithms are not forced to be arithmetic. Option no fixed progression contradicts the clean derived condition. Hence the answer is arithmetic progression. This duality runs both ways: applying the exponential function, the inverse of the logarithm, turns an arithmetic progression of exponents back into a geometric progression of values, so logarithms and exponentials act as a translation dictionary between additive and multiplicative structure, a theme JEE Advanced returns to repeatedly. Plausibility check: for the GP 1, 10, 100 in base ten the logarithms are 0, 1, 2, which are equally spaced and therefore arithmetic, directly confirming the general result.

This hard difficulty mathematics question is from the chapter sequence and series, covering the topic of geometric progression with logarithms. It appeared in the 2025 exam.

Looking for more practice? Explore all mathematics questions or browse sequence and series questions on RankGuru.