How to change from standard for to vertex form

Standard form is
ax^2+bx+c=y
to change to vertex form
complete the square

HOW TO COMPLETE THE SQUARE
first, isolate the x terms
(ax^2+bx)+c=y
factor out a
a(x^2+(b/a)x)+c=y
take 1/2 of the coefient of the x term and square it
(b/a) time 1/2=b/(2a), square it,
now add positive and negative inside parenthasees
a(x^2+(b/a)x+-)+c=y
factor perfect square
a((-a)+c=y
distribute

 
that is vertex form and how to complete the square

for ax^2+bx+c=y
vertex form is