Prove or disprove the following:

(a) 5n² - 2n + 26 O(n²)

(b) a 1: aⁿ O(n!)

(c) a 1: 2^n+a O(2ⁿ)

(d) a > 1: O(log₂n)) (f(n) O(log_an))

(e) 2ⁿ O(n^{log^2(n)})

(f) 2^{2^(n+1)} O(2^{2^n})