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#