Since it's ugly to find the factors of 784, let's try to simplify this a bit.
Let's divide everything by 49 to yield a monic polynomial.
[tex] n^{2} - \frac{56n}{49} + \frac{16}{49}[/tex]
[tex] n^{2} - \frac{8n}{7} + \frac{16}{49}[/tex]
[tex] n^{2} - 2\frac{4n}{7} + \frac{16}{49}[/tex]
We now have a perfect square; [tex]\frac{16}{49} = \frac{4^{2}}{7^{2}}[/tex]
So, we can say that it becomes:
[tex](n - \frac{4}{7})^{2}[/tex]
[tex]= (7n - 4)^{2}[/tex]
