3) Let Hn denote the nth Harmonic number. (Recall that H,-Y. Use mathematical induction on n to show that H2 for all non-negative integers n. 4) Let f(n)-Deinef(n) to be the function f composed with itself k times. More formally, n+2 fo (n)-n and fk (n)-f(fk-1 (n)), for all positive integers k. Using induction on k, prove that for all positive integers k, fk(n) = (2.1)n+2E (Hint: The algebra can be messy if you don't