Show that the function f(x,y)=8x2Solve the constraint for y.y=?Substitute into f.f(x,y)=?

y subject to 3x−y=9 does not have an absolute minimum or maximum.​ (Hint: Solve the constraint for y and substitute into​ f.)

Determine the behavior of f as x approaches −∞.

lim

x→−∞ f(x,y)=?

Determine the behavior of f as x approaches ∞.

lim

x→∞ f(x,y)=?

Does this show that f does not have an absolute maximum or​ minimum?

no or yes?