$$\left. \begin{array} { l } { - x ^ { 2 } - 4 x + 15 = 0 } \\ { ? } \\ { x = ? } \end{array} \right.$$
$x=-\left(\sqrt{19}+2\right)\approx -6.358898944\text{, }y=-\left(\sqrt{19}+2\right)\approx -6.358898944$
$x=\sqrt{19}-2\approx 2.358898944\text{, }y=\sqrt{19}-2\approx 2.358898944$
$x=-\sqrt{19}-2\approx -6.358898944\text{, }y=-\sqrt{19}-2\approx -6.358898944$
$x=\sqrt{19}-2\approx 2.358898944\text{, }y=\sqrt{19}-2\approx 2.358898944$
