What is the third-degree Taylor polynomial P3(x)P_3(x)P3(x) for f(x)=xf(x) = \sqrt{x}f(x)=x centered at a=1a=1a=1?
1+12(x−1)−18(x−1)2+116(x−1)31 + \frac{1}{2}(x-1) - \frac{1}{8}(x-1)^2 + \frac{1}{16}(x-1)^31+21(x−1)−81(x−1)2+161(x−1)3
1+12(x−1)−14(x−1)2+18(x−1)31 + \frac{1}{2}(x-1) - \frac{1}{4}(x-1)^2 + \frac{1}{8}(x-1)^31+21(x−1)−41(x−1)2+81(x−1)3
1−12(x−1)+18(x−1)2−116(x−1)31 - \frac{1}{2}(x-1) + \frac{1}{8}(x-1)^2 - \frac{1}{16}(x-1)^31−21(x−1)+81(x−1)2−161(x−1)3