You want the form:

You have zeros at (-2, 0) and (8, 0) and a y-intecept of (0, 8).

Plugging these points into the equation individually:

Or:

Probably the simplest thing to do here would be to take the last equation:

and sub it into the top two equations.

==>

==>

These turn into:

I'm going to multiply the top equation by 2 and add the bottom equation to it:

--------------------------------

Thus

So

Becomes

Finally:

So

-Dan