D $3\mathrm{.}1-12.$ Consider the following problem, where the value of $c_1$ has not yet been ascertained.

Maximize $,Z=c_1{x}_1+x_2,$

subject to

$x_1+x_{2}6$

$x_1+2x_{2}10$

and

$x_{1}0,x_{2}0.$

Use graphical analysis to determine the optimal solution$($s$)$ for $(x_1,x_2)$ for the various possible values of