Question 83654
take half of the coefficient of the x term, square it, and add (to both sides) ... then factor, and take square root


x^2-4x+(-2)^2=(-1/2)+(-2)^2 ... x^2-4x+4=7/2 ... (x-2)^2=7/2 ... {{{x-2=sqrt(7/2)}}} ... {{{x=(2 +- sqrt(7/2))}}}