每日一题

Mathematics>Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer.

If 2^a = 4^b, which of the following expresses a in terms of b?

(A) b/2
(B) b
(C) 2b
(D) 4b
(E) 2^b

答案和解析

答案：C

解析：

Choice (C) is correct. Since 4 = 2^2, it follows that 4^b = (2^2)^b = 2^(2b). Therefore, 2^a = 4^b = 2^(2b), from which it follows that a = 2b.