I have a couple of questions relating to Taylor expansions.

1) I have a function f(s) and I'm trying to use a Taylor expansion to look at the change in value of f over a small change in s, $\displaystyle \delta s$, how would I represent

$\displaystyle f(s + \delta s)$ as a Taylor expansion?

2) If I have a function of 2 variables, how would I find a Taylor expansion for f(s,t)?