[tex]1.[/tex]

[tex]11 {x}^{2} = 99 \\ {x}^{2} = 9 \\ x =±3[/tex]

[tex] {5x}^{2} - 45x = 0 \\ 5x(x - 9) = 0 \\ 5x = 0 \: \: \: \: \: x = 0 \\ x - 9 = 0 \: \: \: \: \: x = 9[/tex]

[tex] {9x}^{2} - 81 = 0 \\ {9x}^{2} = 81 \\ {x}^{2} = 9 \\ x = ±3[/tex]

[tex] {3x}^{2} + 27 = 0 \\ {3x}^{2} = - 27 \\ {x}^{2} = - 9 \\ x = ∅[/tex]

[tex] { - 13x}^{2} = 0 \\ {x}^{2} = 0 \\ x = 0[/tex]

[tex]2.[/tex]

[tex] {5x}^{2} - 7x + 2 = 0 \\ D = {( - 7)}^{2} - 4 \times 5 \times 2 = 49 - 40 = 9 \\ x1x2 = \frac{ - ( - 7)± \sqrt{9} }{2 \times 5} = \frac{7±3}{10} \\ x1x2 = 0.4 \: ; \: 1[/tex]

[tex]5(1 - {x}^{2} ) = 6(3 - {x}^{2} ) - 13 \\ 5 - {5x}^{2} = 18 - {6x}^{2} - 13 \\ - {5x}^{2} + {6x}^{2} + 5 - 18 + 13 = 0 \\ {x}^{2} = 0 \\ x = 0[/tex]

[tex]12(x - 8) = {(x + 8)}^{2} \\ 12x - 96 = {x}^{2} + 16x + 64 \\ {x}^{2} + 16x + 64 - 12x + 9 6= 0 \\ {x}^{2} + 4x + 160 = 0 \\ D = { 4}^{2} - 4 \times 1 \times 160 = 16 - 640 = - 626 \\ x = ∅[/tex]

Только 2 смог