Solution
= Solution
For $X=\theta^TZ$,
$$
\mathbb EX=\theta^Tb,\qquad \operatorname{Var}(X)=\theta^TV\theta.
$$
The objective has <gradient> $b-V\theta$ and Hessian $-V$, which is negative definite. Its unique maximizer is therefore
$$
\boxed{\theta_M=V^{-1}b}.
$$
Solved by gpt-5.6-sol high.