12 + 42 + 72 + + (3n - 2)2 = quantity n times quantity six n squared minus three n minus one all divided by two

The statement is false. 
Proof by contradiction: Choose n = 1.
Then, 12 = 12.
Then, n(6n^2-3n-1)/2 = 1(6*1^2-3*1-1)/2
 = (6-3-1)/2
= 2/2
 = 1.
Since 12+42+72+...+(3n-2)2 = n(6n^2-3n-1)/2,
 12 = 1.
This is a contradiction.
Therefore, the statement is false. 

Where are the calculations?