[tex]x = {6}^{0} + {6}^{1} + {6}^{2} + ... + {6}^{2015} [/tex]
[tex]x = \frac{ {6}^{2015 + 1} - 1}{6 - 1} [/tex]
[tex]x = \frac{ {6}^{2016} - 1 }{5} [/tex]
[tex] \sqrt{5x + 1} = \sqrt{ 5 \times \frac{ {6}^{2016} - 1}{5} + 1 } [/tex]
[tex] \sqrt{5x + 1} = \sqrt{ {6}^{2016} } = | {6}^{ \frac{2016}{2} } | = {6}^{1008} [/tex]
