The maximum rate of change occurs in the direction of the gradient vector at (1, 1, 1).
[tex]T(x,y,z)=e^{-x^2-2y^2-3z^2}\implies\nabla T(x,y,z)=\langle-2x,-4y,-6z\rangle e^{-x^2-2y^2-3z^2}[/tex]
At (1, 1, 1), this has a value of
[tex]\nabla T(1,1,1)=\langle-2,-4,-6\rangle e^{-6}[/tex]
so the captain should move in the direction of the vector [tex]\langle-1, -2, -3\rangle[/tex] (which is a vector pointing in the same direction but scaled down by a factor of [tex]2e^{-6}[/tex]).
