How do you solve 3x^2+8=12x by using the Quadratic Formula?

1 Answer
Jul 21, 2015

x = 2 +- 4/sqrt(3)
color(white)("XXXX")color(white)("XXXX")(solved using the Quadratic Formula)

Explanation:

Using the standard quadratic form:
color(white)("XXXX")ax^2+bx+c=0
the quadratic formula for the solutions is
color(white)("XXXX")x = (-b+-sqrt(b^2-4ac))/(2a)

It will be necessary, first to convert the given equation:
color(white)("XXXX")3x^2+8=12x
into the standard form (by subtracting (12x) from both sides):
color(white)("XXXX")3x^2-12x+8 = 0

Therefore, using:
color(white)("XXXX")a= 3color(white)("XXXX")b=-12color(white)("XXXX")c=8

The quadratic formula gives
color(white)("XXXX")x = (12 +-sqrt((-12)^2 - 4(3)(8)))/(2(3))

color(white)("XXXX")x = (12 +-sqrt(144 -96))/6

color(white)("XXXX")x = 2 +- 4/sqrt(3)