Solution
Reason 1:
[tex]\begin{gathered} y=8x^2+80x+72 \\ \\ \Rightarrow\frac{dy}{dx}=16x+80 \\ \\ \frac{d^2y}{dx^2}=16>0(\text{ Minimum\rparen} \end{gathered}[/tex]Reason 2:
Since the coefficient of x is positive, the graph is going to be minimum.
Maximum value does not exist.
