Respuesta :

x^2 = 81
x = 
±√81
x = ±9

x^2 = -9 no solutions 

x^2 = 20
x = 
±√20
x = ±2√5

[tex]3x^2 = 125 \\ x^2 = \frac{125}{3} \\ x=б \sqrt{ \frac{125}{3} } [/tex]