[tex]a) \\ {x}^{3} - 4x = 0 \\ x( {x}^{2} - 4) = 0 \\ x(x - 2)(x + 2) = 0 \\ x_{1} = 0 \\ x - 2 = 0 \: = > x_{2} = 2 \\ x + 2 = 0 \: = > x_{3} = - 2 \\ x_{1}+ x_{2} + x_{3} = 0 + 2 - 2 = 0[/tex]
b)
[tex] {0}^{2} + {2}^{2} + {( - 2)}^{2} = 4 + 4 = 8 [/tex]
c)
[tex]x_{1}x_{2}x_{3} + x_{1}x_{2}x_{3} + x_{1}x_{2}x_{3} - {x_{1}}^{3} - {x_{2}}^{3} - {x_{ 3}}^{3} = 0 + 0 + 0 - 0 - 8 + 8 = 0[/tex]
