Answer:
[tex] x = 4 + \sqrt{11}, \: \: x = 4 - \sqrt{11} [/tex]
Step-by-step explanation:
[tex] {x}^{2} -8x + 5 = 0 \\ \\ {x}^{2} - 8x + {4}^{2} = - 5 + {4}^{2} \\ \\ {(x - 4)}^{2} = - 5 + 16 \\ \\ {(x - 4)}^{2} = 11 \\ \\ x - 4 = \pm \sqrt{11} \\ \\ x = 4 \pm \sqrt{11} \\ \\ x = 4 + \sqrt{11}, \: \: x = 4 - \sqrt{11} [/tex]