If f(x) = 3^(x+1) and g(x) = 9^(x-1), for what value of x is f(x) = g(x)?

A 1

B 2

C 3

D 4

✓ Correct Answer: Option C

Set f(x) = g(x): 3^(x+1) = 9^(x-1). Since 9 = 3², we can write 3^(x+1) = (3²)^(x-1) = 3^(2(x-1)). Equating the exponents: x+1 = 2(x-1) => x+1 = 2x-2 => 3 = x.

💡 Why is C) the correct answer?

The correct answer to the question "If f(x) = 3^(x+1) and g(x) = 9^(x-1), for what value of x is f(x) = g(x)?" is Option C: 3.

The other options — A) 1, B) 2, D) 4 — are incorrect for this GMAT Exam Prep question. As explained above: Set f(x) = g(x): 3^(x+1) = 9^(x-1). Since 9 = 3², we can write 3^(x+1) = (3²)^(x-1) = 3^(2(x-1)). Equating the exponents: x+1 = 2(x-1) => x+1 = 2x-2 => 3 = x.

📚 About This GMAT Exam Prep Practice Question

This 4-level GMAT Exam Prep question from the Quantitative Reasoning topic is part of BrainForge Quiz's free exam preparation library. Each question includes the correct answer and a detailed explanation to help you understand the underlying concept, not just memorize the answer.

How to use this page: Read the question above, consider all four options (A through D), then check the highlighted correct answer and explanation. For active timed practice, start a free GMAT Exam Prep practice test or use flashcards for spaced repetition review.

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If f(x) = 3^(x+1) and g(x) = 9^(x-1), for what value of x is f(x) = g(x)?

✓ Correct Answer: Option C

📚 About This GMAT Exam Prep Practice Question

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