The quadratic formula states:
For color(red)(a)x^2 + color(blue)(b)x + color(green)(c) = 0, the values of x which are the solutions to the equation are given by:
x = (-color(blue)(b) +- sqrt(color(blue)(b)^2 - (4color(red)(a)color(green)(c))))/(2 * color(red)(a))
Substituting:
color(red)(6) for color(red)(a)
color(blue)(-12) for color(blue)(b)
color(green)(1) for color(green)(c) gives:
x = (-color(blue)((-12)) +- sqrt(color(blue)((-12))^2 - (4 * color(red)(6) * color(green)(1))))/(2 * color(red)(6))
x = (color(blue)(12) +- sqrt(144 - 24))/12
x = (color(blue)(12) +- sqrt(120))/12
x = (color(blue)(12) +- sqrt(4 * 30))/12
x = (color(blue)(12) +- 2sqrt(30))/12
Or
x = 1 +- sqrt(30)/6