Question Number 48306 by Messias last updated on 21/Nov/18
$$\mathrm{x}^{\mathrm{2}} +\mathrm{4x}+\mathrm{1}=\mathrm{9} \\ $$
Answered by MJS last updated on 21/Nov/18
$${x}^{\mathrm{2}} +{px}+{q}=\mathrm{0}\:\Rightarrow\:{x}=−\frac{{p}}{\mathrm{2}}\pm\sqrt{\frac{{p}^{\mathrm{2}} }{\mathrm{4}}−{q}} \\ $$$$\mathrm{in}\:\mathrm{this}\:\mathrm{case}:\:{p}=\mathrm{4};\:{q}=−\mathrm{8} \\ $$$$\Rightarrow\:{x}=−\mathrm{2}\pm\mathrm{2}\sqrt{\mathrm{3}} \\ $$