Question Number 31018 by jasno91 last updated on 02/Mar/18
Commented by rahul 19 last updated on 02/Mar/18
$${sum}\:{of}\:{roots}\:=−\:\frac{{coefficient}\:{of}\:{b}}{{coefficient}\:{of}\:{a}} \\ $$$$\:{let}\:\mathrm{3}{rd}\:{root}=\:\zeta \\ $$$$\Rightarrow\:\sqrt{\mathrm{3}}\:+\left(\:−\sqrt{\mathrm{3}}\:\right)+\zeta\:=\:\frac{−\mathrm{1}}{\mathrm{2}}. \\ $$$${hence}\:\zeta\:=\:−\frac{\mathrm{1}}{\mathrm{2}}\:. \\ $$