Verified answer

[tex]x = - 0.8 \\ {x}^{2} = ( - 0.8) {}^{2} = 0.64[/tex]

[tex]x = 5 \\ {x}^{2} = 5 {}^{2} = 25[/tex]

[tex]x = - \frac{2}{3} \\ {x}^{2} = ( - \frac{2}{3} ) {}^{2} = \frac{4}{9} [/tex]