Question

-x ao quadrado - 8 = - 6x

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Answer 1

Oie, tudo bom?

$- x {}^{2} - 8 = - 6x \\ - x {}^{2} + 6x - 8 = 0 \: \: \: \: \: \: . \: ( - 1)\\ x {}^{2} - 6x + 8 = 0$

$\boxed{a = 1 \: , \: b = - 6 \: , \: c= 8}$

$x = \frac{ - b± \sqrt{b {}^{2} - 4ac} }{2a} \\ x = \frac{ - ( - 6)± \sqrt{( - 6) {}^{2} - 4 \: . \: 1 \: . \: 8 } }{2 \: . \: 1} \\ x = \frac{6± \sqrt{36 - 32} }{2} \\ x = \frac{6± \sqrt{4} }{2} \\ x = \frac{6±2}{2} \\ x = \frac{6 + 2}{2} = \frac{8}{2} = \boxed{4} \\ x = \frac{6 - 2}{2} = \frac{4}{2} = \boxed{2}$

$\boxed{S = \left \{2\:,\:4\right \}}$

Att. NLE Top Shotta