Determine the coefficient of x3x^3x3 in the Maclaurin series of the function: f(x)=xcos(x)f(x) = \frac{x}{\cos(x)}f(x)=cos(x)x
12\frac{1}{2}21
−12-\frac{1}{2}−21
16\frac{1}{6}61
000