(Note: When I say delta, I mean the little triangle thing usually meaning change, I can't find the HTML code for it.)

Alright, I have a the function f(x) = x^2+3x-1

I then need to evaluate for f(x+deltax). I know that then should look something like x^2+3x-1 + deltax^2+3x-1.

Please verify that is essentially what should happen, and then help me understand what exactly I am supposed to do with the delta in front of the "x" value.