${\displaystyle x={\frac {-b\pm {\sqrt {b^{2}-4ac}}}{2a}}}$
 ${\displaystyle x_{1}={\frac {-b+{\sqrt {b^{2}-4ac}}}{2a}}}$ y ${\displaystyle \ x_{2}={\frac {-b-{\sqrt {b^{2}-4ac}}}{2a}}}$