Question 977272
First find the feasible region.
*[illustration dd9.JPG].
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The extrema occur at the vertices.
(0,0) : {{{f=3(0)+1(0)=0}}}
(0,9) : {{{f=3(0)+1(9)=9}}}
(7,0) : {{{f=3(7)+1(0)=highlight(21)}}}
(14/3,2) : {{{f=3(14/3)+1(2)=16}}}