Question

encontre as raizes da função f(x)

Answer 1

$f(x)=x^2+8x+9\\X=\frac{-8\pm\sqrt{\Delta}}{2}\ |\Delta = 64-4.9=64-36=28\ |X=\frac{-8\pm\sqrt{28}}{2}\implies\\ \\X=\frac{-8\pm2\sqrt{7}}{2}= \left \{ {{x'=-4+\sqrt{7}} \atop {x''=-4-\sqrt{7}}} \right. \ |(\sqrt{28}\approx5,3=\sqrt{2^2.7}=2\sqrt{7}\ \\sqrt{7}\approx2,64\implies 2,64.2\approx \sqrt{28}) \\ S= \{x\in\mathbb{R}|\ x=-8\pm\sqrt{7}\therefore(-8+\sqrt{7},-8\sqrt{7})\}$

As raízes são os pontos onde a função é nula, encontramos as duas raízes da função.