Since there is no feasible region defined, there is no answer possible.
If we knew the values of 'x' and 'y', and the boundaries of the feasible region, we could answer that question quickly and easily.
It would depend on the feasible region.
Since x and y can get smaller and smaller without a limit, there is no minimum for the value of 3x+3y.
The vertex has a minimum value of (-4, -11)
(1/x) + (1/y) + (1/z) is a minimum value when x=y=z=10. Symmetry gives either maximum or minimum value.
It is 18.
2x+2y
The answer depends on the feasible region and there is no information on which to determine that.
If we knew the values of 'x' and 'y', and the boundaries of the feasible region, we could answer that question quickly and easily.
It is 18.
It would depend on the feasible region.
42
maximum value of 6y+10y
14
(6x)(5y)
The answer obviously depends on what the boundaries of the feasibility region are.
78