Determine the partial derivative fu(1,1)f_u(1, 1)fu(1,1) for the multivariable function f(u,v)=u+3vf(u, v) = \sqrt{u + 3v}f(u,v)=u+3v.
14\frac{1}{4}41
12\frac{1}{2}21
18\frac{1}{8}81
111