Question

Encontre as raizes de x^2 -2x-8=0. com cálculos

Answer 1

Resposta:

Explicação passo-a-passo:

$Aplicando~a~f\'{o}rmula~de~Bhaskara~para~x^{2}-2x-8=0~~\\e~comparando~com~(a)x^{2}+(b)x+(c)=0,~temos~a=1{;}~b=-2~e~c=-8\\\\\Delta=(b)^{2}-4(a)(c)=(-2)^{2}-4(1)(-8)=4-(-32)=36\\\\x^{'}=\frac{-(b)-\sqrt{\Delta}}{2(a)}=\frac{-(-2)-\sqrt{36}}{2(1)}=\frac{2-6}{2}=\frac{-4}{2}=-2\\\\x^{''}=\frac{-(b)+\sqrt{\Delta}}{2(a)}=\frac{-(-2)+\sqrt{36}}{2(1)}=\frac{2+6}{2}=\frac{8}{2}=4\\\\S=\{-2,~4\}$