I need some assistance

Question

Prove By PMI

1+4+7+.........+3n-2 = n(3n-1)/2

Answer 1

Since the formula is trivially true to n = 1,

you need to show that it is true for n+1, i.e.

(n+1)(3n+2)/2 = [n(3n-1)/2] + 3n+1