Determine the third Taylor Polynomial of f(x) at x=0 for the function

f(x)=(x+1)^-1/2

My answer is:

p(x)=1+1/2x+3/8x^2+5/16x^3

Is this correct, and is it called the third Taylor polynomial because it ends in x^3? Also, is the p(x) correct or should it be written another way?