How do I solve this equation and check the solutions?

[tex] : \implies \sf {\big( \sqrt{20 - 8x} \:\big)}^{2} = x^2 \\ \\ [/tex]
[tex]:\implies \sf {20 - 8x} = {x}^{2} \\ \\ [/tex]
[tex] : \implies\sf{ {x}^{2} + 8x - 20 = 0 } \\ \\ [/tex]
[tex]: \implies\sf{ {x}^{2} + (10 - 2)x - 20 = 0 } \\ \\ [/tex]
[tex]: \implies\sf{ {x}^{2} + 10x - 2x - 20 = 0 } \\ \\ [/tex]
[tex] : \implies\sf{ x(x + 10) - 2(x + 10 )= 0 } \\ \\ [/tex]
[tex] :\implies\sf{( x + 10 )(x - 2)= 0 } \\ \\[/tex]
[tex] : \implies\sf x + 10 = 0 \: or \: x - 2 = 0 \\ \\ [/tex]
[tex]: \implies\sf x = 0 - 10\: or \: x = 0 + 2\\ \\ [/tex]
[tex]: \implies \underline{\boxed{ \bf{x = - 10 \: or \: x = 2}}}[/tex]
[tex]\huge {\therefore} [/tex] The roots of this equation are -10 and 2.