Find the second-degree Taylor polynomial P2(x)P_2(x)P2(x) for f(x)=cos(x)f(x) = \cos(x)f(x)=cos(x) centered at a=0a = 0a=0.
1−x1 - x1−x
1−x221 - \frac{x^2}{2}1−2x2
1+x21 + x^21+x2
1−x241 - \frac{x^2}{4}1−4x2