Question

a) x2– 3x - 28 = 0
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Answer 1

${x}^{2} - 3x - 28 = 0 \\ \\ x = \frac{ - ( - 3) + - \sqrt{( - 3 {)}^{2} - 4 \times 1 \times ( - 28) } }{2 \times 1} \\ \\ x = \frac{3 + - \sqrt{9 + 112} }{2} \\ \\ x = \frac{3 + - \sqrt{121} }{2} \\ \\ x = \frac{3 + - 11}{2}$

Vamos separar a raizes

$x_{1} = \frac{3 - 11}{2} \\ \\ x_{1} = \frac{ - 8}{2} \\ \\ x_{1} = - 4$

$x_{2} = \frac{3 + 11}{2} \\ \\ x_{2} = \frac{14}{2} \\ \\ x_{2} = 7$

S = { -4 e 7}