Question 885893
You have asked the same general question using three separate example functions, each in its own posting.  You would really benefit from the lesson in this link:

<a href="http://www.algebra.com/tutors/Completing-the-Square-to-Solve-General-Quadratic-Equation.lesson?content_action=show_dev">Completing the Square to Solve General Quadratic Equation</a>