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algebra senior
Problem
The number is between and . How many pairs of integers are there such that and
(A)
(B)
(C)
(D)
Solution
Between any two consecutive powers of there are either or powers of (because ). Consider the intervals . We want the number of intervals with powers of . From the given that , we know that these intervals together have powers of . Let of them have powers of and of them have powers of . Thus we have the system from which we get , so the answer is .
Final answer
B