Graphing a Quadratic Function Given in General Form

If I understand correctly, the formula is:

Here's what I have:

First:

=

Easy enough. Now though...

Doing it that way comes up with wildly incorrect answers. I'd type it out but it's just all wrong. The answer in the book is...

However, doing...

does get me

So that's really

So my question is: Why? I'm missing something in the translation and I'm hoping to get some kind of answer. Thanks for any and all help.

Re: Graphing a Quadratic Function Given in General Form

Quote:

Originally Posted by

**Trypanosoma** If I understand correctly, the formula is:

Being psychic, I know that you meant the formula for the vertex coordinates of the parabola ax^2+bx+c (Smile).

Quote:

Originally Posted by

**Trypanosoma**

Should be

Quote:

Originally Posted by

**Trypanosoma**

Should be

Quote:

Originally Posted by

**Trypanosoma** Doing it that way comes up with wildly incorrect answers.

Not wildly incorrect; the difference between this and the correct answer is only 1/33.

Quote:

Originally Posted by

**Trypanosoma** So that's really

So my question is: Why?

The y-coordinate of the vertex is .