Establish a big-O relationship, find witnesses C and k such that |f (x)| ≤ C|g(x)| whenever x > k.
Determine whether each of these functions is O(x).
a) f (x) = 10
b) f (x) = 3x + 7
c) f (x) = x2 + x + 1
d) f (x) = 5 log x
e) f(x) = ⌊x⌋
f) f(x) = ⌈x/2⌉