Respuesta :

Step-by-step explanation:

40 - x^2 = 0...subtract 40

-x^2 = -40....multiply both sides by -1

x^2 = 40

x = (+ - ) sqrt 40

x = (+ - ) sqrt 4 * 10

x = (+ - ) 2 sqrt 10

x = 2 sqrt 10, and x = -2 sqrt 10