Grade 10 x = -b/2a is the axis of symmetry, Finding the equation of a quadratic in factored form

How to use x = - b/2a to convert from standard form to vertex form! x = - b/2a gives you the x coordinate of the vertex which is also the value for the equation of the axis of symmetry! AMAZING
Also how to find the equation of a quadratic in factored form when you are given the x-intercepts (or zeros of the function) and the y-intercept.