Let .
If is periodic, find the number of possible non-negative integral value(s) of .
Notations :
denotes the floor function .
denotes the fractional part function .
denotes the absolute value function .
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First of all, m 2 − 3 m + 1 ≤ 1 and m 2 − 3 m + 1 ≥ − 1 . The union of these inequalities shows 0 ≤ m ≤ 1 and 2 ≤ m ≤ 3 . Since the question asks for non-negative integral values, m can be 0 , 1 , 2 , or 3 . Also, ⌊ e m − 4 ⌋ = 0 since m = 0 , 1 , 2 , or 3 are all less than 4 . As a result, the latter part of the function becomes 0 . Since for the 4 possible values for m , a r c s i n ( m 2 − 3 m + 1 ) is not 0 and k* s e c ( ∣ x ∣ ∗ 0 . 3 3 3 3 ) is periodic for some real number k , there are 4 possible values for m that make f ( x ) periodic.