It is calculated using the quadratic formula
[tex]x\text{ = }\frac{-b\text{ }\pm\sqrt[]{b^2-4ac}}{2a}[/tex]In the equation
[tex]x^2-5x+1=0[/tex]a = 1, b = -5 and c = 1
Substitute the given to the quadratic formula
[tex]\begin{gathered} x\text{ = }\frac{5+\sqrt[]{21}}{2} \\ x\text{ = }\frac{5-\sqrt[]{21}}{2} \end{gathered}[/tex]