Logistic Growth questions.

The formulas for Logistic growth in the solutions/book are a bit different from the formulas given to us on Friday.
For example, on Friday we learned that
However, in the book the formula is
Also, we learned that
But in the book they have
I remember Mrs. Carlson wrote up different ways to write P but I didn't copy those down, and I wasn't sure if that was just a different way to write the formula.
I was hoping someone could clear this up because I'm really confused.
Which one do we use for the homework?
Thanks!

EDIT: I just read the e-mail.
I got it now. :]