How do you solve #x^2-3x=28# by completing the square?

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Answer 1 · 2018-03-03T07:48:49

#color(green)(x = 7, -4#

#x^2 - 3x = 28#

Add # (3/2)^2# to both sides.

#x^2 - (2 * (3/2) * x) + (3/2)^2 = 28 + (3/2)^2#

#(x-3/2)^2 = 121 /4 = (11/2)^2#

#x - 3/2 = +- 11 /2#

#x = +- 11/2 + 3/2#

#color(green)(x = 7, -4#