How do you solve $5x^2−8x−4=0$ using the quadratic formula?

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Answer 1 · 2016-06-04T03:07:52

$x = 2$ , $x = -2/5$

The quadratic formula states that given a quadratic equation

$ax^2 + bx + c = 0$

Its roots can be obtained using the equation below

$x = (-b +- sqrt(b^2 - 4ac))/(2a)$

$5x^2 - 8x - 4 = 0$

$=> x = (-(-8) +- sqrt((-8)^2 - 4(5)(-4)))/(2(5))$

$=> x = (8 +- sqrt(64 + 80))/10$

$=> x = (8 +- sqrt(144))/10$

$=> x = (8 +- 12)/10$

$=> x = 20/10 => x = 2$
$=> x = -4/10 => x = -2/5$

How do you solve 5x^2−8x−4=05x^2−8x−4=0 using the quadratic formula?