虽然说
If 2^a = 4^b, which of the following expresses a in terms of b?
(A) b over 2
(B) b
(C) 2 times b
(D) 4 times b
(E) 2^b
解释：
Since 4 = 2^2, the expression 4^b can be written as (2^2)^b.
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.
正确答案是C。
When the positive integer n is divided by 5, the remainder is 0. What is the remainder when 3 times n is divided by 5?
(A) 0
(B) 1
(C) 2
(D) 3
(E) 4
解释：
If the remainder is 0 when an integer is divided by 5, then the integer is a multiple of 5.
Choice (A) is correct. When the positive integer n is divided by 5, the remainder is 0. It follows that n is a multiple of 5. Therefore, 3n is also a multiple of 5, and so the remainder when 3n is divided by 5 is likewise 0.
正确答案是A。
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