How do you solve $x^2 = 8x - 20$ using the quadratic formula?

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Answer 1 · 2016-03-04T14:14:09

The solutions are:
$color(blue)(x=4+ 2i$

$color(blue)(x=4- 2i$

$x^2-8x+20=0$

The equation is of the form $color(blue)(ax^2+bx+c=0$ where:
$a=1, b=-8, c=20$

The Discriminant is given by:

$Delta=b^2-4*a*c$
$= (-8)^2-(4*1 *20)$
$= 64-80=-16$

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

$x = (-(-8)+-sqrt(-16))/(2*1) = (8+- 4i)/2$

$x=( 2(4+- 2i))/2$

$x=( cancel2(4+- 2i))/cancel2$

$color(blue)(x=4+ 2i$

$color(blue)(x=4- 2i$

How do you solve x^2 = 8x - 20x^2 = 8x - 20 using the quadratic formula?