Take it step-by-step.
Take pen and paper. Plot a cartesian coordinate system with x1 and x2 at the axes.
For 1.6 you have 2 linear constraints. Plot the lines of their boundary, sketch in the regions
where they are satisfied. That gives you the allowed region for your optimization. Calculate
the gradient of your function F, plot that arrow (since it is a linear function in x1 and x2). Plot that
arrow on the graph.
For 1.7 do the same. Step by-step. Here there will be another couple of steps since you have
additional constraints.
For doing this with matlab: have a look at pcolor, double and meshgrid.
HTH
