[tex]x^{2} + 4x = 13[/tex]
[tex]x^{2} + 4x - 13 = 13 - 13[/tex]
[tex]x^{2} + 4x - 13 = 0[/tex]
[tex]x = \frac{-4 +/- \sqrt{4^{2} - 4(1)(13)}}{2(1)} [/tex]
[tex]x = \frac{-4 +/- \sqrt{16 - 52}}{2} [/tex]
[tex]x = \frac{-4 +/- \sqrt{-36}}{2}[/tex]
[tex]x = \frac{-4 +/- \sqrt{36 * (-1)}}{2} [/tex]
[tex]x = \frac{-4 +/- \sqrt{36} \sqrt{-1}}{2} [/tex]
[tex]x = \frac{-4 +/- 6i}{2} [/tex]
[tex]x = \frac{-4 + 6i}{2} [/tex] [tex]x = \frac{-4 - 6i}{2} [/tex]
[tex]x = -2 + 3i[/tex] [tex]x = 2 - 3i[/tex]
