Respuesta :

[tex]\begin{gathered} \text{ x}^2\text{ }=\text{ }\sqrt[]{20^2-18^2} \\ x^2\text{ = }\sqrt[]{400\text{ - 324}} \\ x\text{ = }\sqrt[]{76} \\ x\text{ = 2}\sqrt[]{19} \end{gathered}[/tex]

The second choice is the correct answer