Suppose we want to prove the statement S(n): "If n ≥ 2, the sum of the integers 2 through n is (n+2)(n-1)/2" by induction on n. To prove the inductive step, we can make use of the fact that 2+3+4+...+(n+1) = (2+3+4+...+n) + (n+1) Find, in the list below an equality that we may prove to conclude the inductive part. a) If n ≥ 3 then (n+2)(n-1)/2 + n + 1 = (n+3)(n)/2 b) If n ≥ 1 then (n+2)(n-1)/2 + n + 1 = (n+3)(n)/2
c) If n ≥ 2 then (n+2)(n-1)/2 + n + 1 = (n+3)(n)/2
d) If n ≥ 1 then (n+2)(n-1)/2 + n + 1 = n(n+3)/2