What would make putting the point directly on the line easier? How could you be more accurate?
(Without actually seeing the line, that is!)

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]