Six out of eight teachers prefer Expo markers to non-brand markers. What is the ratio of teachers who do not prefer Expo markers to those who do?

Use mathematical induction to prove the statement is true for all positive integers n, or show why it is false. 1^2 + 4^2 + 7^2 + + (3n - 2)^2 = [n(6n^2-3n-1)/2]