Resposta:

[tex]a) \: {x}^{2} - 16 = 0 \\ {x }^{2} = 16 \\ x = + - \sqrt{16} \\ x = + - 4 \\ \\ x = - 4 \\ x = 4 \\ \\ x1 = - 4 \\ x2 = 4[/tex]

[tex]b) \: x + 6x = 0 \\ 7x = 0 \\ x = 0[/tex]

[tex]c) \: 2 {x}^{2} - 22x = 0 \\ 2x \times ( x - 11) = 0 \\ 2x \div (2) \times (x - 11) = 0 \\ x \times (x - 11) = 0 \\ \\ x = 0 \\ x - 11 = 0 \\ \\ x = 0 \\ x = 11 \\ \\ x1 = 0 \\ x2 = 11[/tex]

d) 7x² - 28 = 0 : (7)

x² - 4 = 0

x² = 4

x = +- √4

x = +- 2

x = -2

x = 2

x1 = -2

x2 = 2