1-1. Determine if the quadratic function f(x,y,z)=−x2−5y2−4z2−2xy−2yz−2x−4z−5f(x,y,z) = -x^2 - 5y^2 - 4z^2 - 2xy - 2yz - 2x - 4z - 5f(x,y,z)=−x2−5y2−4z2−2xy−2yz−2x−4z−5 has a maximum fmaxf_{max}fmax at (x,y,z)=(x∗,y∗,z∗)(x,y,z) = (x^*, y^*, z^*)(x,y,z)=(x∗,y∗,z∗). If so, find:
(a) (5 points) fmaxf_{max}fmax.
(b) (5 points) (x∗,y∗,z∗)(x^*, y^*, z^*)(x∗,y∗,z∗).
