# I need to find the absolute extrema

• Apr 7th 2010, 06:27 AM
ghow90
I need to find the absolute extrema
This is the problem...

$f(x,y)=3xy-6x-3y+7$
on the closed triangular region, $R$, with vertices $(0,0), (3,0), and (0,5)$

I know I need to find the critical points so I found...

$Fx=3y-6$ and $Fy=3x-3$, right?

So to make $Fx=Fy=0$ the values of $x=1$ and $y=2$ so there is a critical point at $(1,2)$, right?

This is where I go blank on how to finish this.
• Apr 7th 2010, 02:37 PM
HallsofIvy
Quote:

Originally Posted by ghow90
This is the problem...

$f(x,y)=3xy-6x-3y+7$
on the closed triangular region, $R$, with vertices $(0,0), (3,0), and (0,5)$

I know I need to find the critical points so I found...

$Fx=3y-6$ and $Fy=3x-3$, right?

So to make $Fx=Fy=0$ the values of $x=1$ and $y=2$ so there is a critical point at $(1,2)$, right?

This is where I go blank on how to finish this.

Yes, however, the absolute extrema might occur on the boundaries rather than at a critical point.
• Apr 7th 2010, 02:47 PM
ghow90
I understand that but that was the first step in finding the absolute extrema