Step-by-step explanation:
[tex]40 - {x}^{2} = 0 \\ \therefore \: {x}^{2} = 40 \\ \therefore \: x = \pm \sqrt{40} \\ \therefore \: x = \pm \sqrt{4 \times 10} \\ \huge \red{ \boxed{\therefore \: x = \pm 2\sqrt{10}}}[/tex]
Start with
[tex]40-x^2=0[/tex]
Add [tex]x^2[/tex] to both sides:
[tex]x^2=40[/tex]
Take the square root of both sides:
[tex]x=\pm\sqrt{40}=\pm\sqrt{4\cdot 10}=\pm 2\sqrt{10}[/tex]
