) Find the absolute minimum and absolute maximum of

f(x,y)=8−9x+13y

on the closed triangular region with vertices (0,0),(13,0) and (13,15). 

List the maximum/minimum values as well as the point(s) at which they occur. Ignore unneeded answer blanks. 

Minimum value:  

Occurs at ( , ) and ( , ) 

Maximum value:  

Occurs at ( , ) and ( , )