How do you factor and solve $x^{2} - x - 20 = 0$ $x^2 - x - 20 = 0$ ?

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Answer 1 · 2016-06-12T19:11:05

The solutions for the equation are: $x = - 4, x = 5$ $color(blue)(x=-4, x = 5$

$x^{2} - x - 20 = 0$ $x^2 - x - 20 = 0$

The equation is of the form $a x^{2} + b x + c = 0$ $color(blue)(ax^2+bx+c=0$ where:

$a = 1, b = - 1, c = - 20$ $a=1, b=-1, c=-20$

The Discriminant is given by:

$Delta=b^2-4*a*c$

$= (-1)^2-(4 * 1 * (-20))$

$= 1 + 80 = 81$

The solutions are found using the formula:
$x=(-b+-sqrtDelta)/(2*a)$

$x = (-(-1)+-sqrt(81))/(2*1) = (1+- 9 )/2$

$x = (1+ 9 )/2 =10 /2, color(blue)( x= 5$

$x = (1 - 9 )/2 = -8/2 , color(blue)(x= - 4$

How do you factor and solve x^2 - x - 20 = 0x2−x−20=0x^2 - x - 20 = 0?