26 (a) The first four terms of a sequence, S, are 89, 83, 77, 71. (i) Find an expression for Sn, the nth term of this sequence. (ii) Find the smallest value of n for which Sn < 0. (b) The nth term of a different sequence, T, is given by Tn = n^2 - 4n. (i) Find and simplify an expression for Tn+1 - Tn . (ii) The difference between Tp+1 and Tp is 75. Find the value of p.