Question

Given below is the odd-number function. Which of the following are equal to O(8)? 

Answer 1

The answer would be B.
For these, you plug in 8 where there ia a variable. 2(8)-1=15

Answer 2

Here, O(8) = 2(8) - 1 = 16-1 = 15
Also, O(7) + 2 = 2(7) -1 + 2 = 14+1 = 15

In short, Your Answer would be Option B and D

Hope this helps!