1957 AMC 12 Problem 28

Attempt Problem 28 of the 1957 AMC 12 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1957 AMC 12 solutions, or check the answer key.

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28.

If aa and bb are positive and a≠1,a\ne1, b≠1,b\ne1, then the value of blog⁡bab^{\log_b a} is:
dependent upon bb
dependent upon aa
dependent upon aa and bb
zero
one
Answer: B
Concepts:logarithmexponent
Small hint:
Use the inverse relationship between a base-bb logarithm and exponentiation by bb
Big hint:
If u=log⁡ba,u=\log_b a, then bu=ab^u=a
Solution:
By the definition of a logarithm, blog⁡ba=a. b^{\log_b a}=a. Thus the value depends on a,a, not on the choice of admissible base b.b.
Therefore, the correct answer is B.
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