An assignment question I have says
Use the definition to find the first three non-zero terms of the Maclaurin series of f(x) = cos pi x
What does the word "definition" refer to above? Does it mean use the definition of a derivative? Because I've seen that term used a lot in relation to definition of the derivative, or is it more likely use the maclaurin definition of cos x to find cos pi x.
In which case, I think the first three non zero terms are
pi - (pi (x^2))/2!) + (pi(x^4))/4!)