# How do you solve 4x^2 - 2x - 1 = 0?

Aug 7, 2015

Solve $y = 4 {x}^{2} - 2 x - 1 = 0$

Ans: $\frac{1}{4} \pm \frac{\sqrt{5}}{4}$

#### Explanation:

$D = {d}^{2} = {b}^{2} - 4 a c = 4 + 16 = 20 \to d = \pm 2 \sqrt{5}$
$y = \frac{2}{8} \pm \frac{2 \sqrt{5}}{8} = \frac{1}{4} \pm \frac{\sqrt{5}}{4}$