Answer:
[tex]x = -10 + 4 \sqrt7 \ , \ x = -10 - 4 \sqrt7[/tex]
Step-by-step explanation:
x²+20x-12=0
a = 1, b = 20, c = -12
[tex]x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2x}[/tex]
[tex]x = \frac{-20 \pm \sqrt{448}}{2}\\\\x = \frac{-20 \pm \sqrt{8 \times 8 \times 7}}{2}\\\\x = \frac{-20 + 8\sqrt{7}}{2} \ , \ x = \frac{-20 - 8 \sqrt7}{2}\\\\x = \frac{-10 + 4\sqrt{7}}{1} \ , \ x = \frac{-10 - 4 \sqrt7}{1}\\\\x = -10 + 4 \sqrt7 \ , \ x = -10 - 4 \sqrt7[/tex]
