Question

√b² - 4ac, para a= -4, b = 20 e c= -25

Answer 1

ax² + bx + c = 0

Sendo a ≠ 0

a = -4
b = 20
c = -25

$x = \frac{-b \pm \sqrt{\Delta}}{2a} \\\\ \Delta = b^{2} - 4ac$

$x = \frac{-20 \pm \sqrt{20^{2} - 4 \cdot (-4) \cdot (-25)}}{2 \cdot (-4)} \\\\ x = \frac{-20 \pm \sqrt{400 - 400}}{-8} \\\\ x' = \frac{-20 + 0}{-8} = 2,5 \\ x'' = \frac{-20 - 0}{-8} = 2,5$
S = {2.5, 2.5}