From 2019. And, dare I say it, still a waste of time. In my not-so-humble opinion you either know enough algebra to understand that, for non-zero a, 0 = a x^2

From 2019. And, dare I say it, still a waste of time. In my not-so-humble opinion you either know enough algebra to understand that, for non-zero a, 0 = a x^2 + b x + c <=> 0 = x^2 + b/a x + c/a <=> 0 = (x + b/2a)^2 - b^2/4a^2 + c/a <=> (x + b/2a)^2 = (b^2 - 4 a c) / 4a^2 or you need to improve your basic algebra skills - not search for a better derivation of this particular formula.