Question

$2x^{2}$ -8x-2=0

Answer 1

2x² - 8x - 2 = 0

x² - 4x - 1 = 0

∆ = (-4)² - 4.1.(-1)

∆ = 16 + 4

∆ = 20

$x = \frac{ - ( - 4) ± \sqrt{20} }{2 \times 1}$

$x = \frac{4 ± 2 \sqrt{5} }{2}$

$x' = \frac{4 + 2 \sqrt{5} }{2}$

$x" = \frac{4 - 2 \sqrt{5} }{2}$

$x' = 2 + \sqrt{5} \\ x" = 2 - \sqrt{5}$