Accepted Answer
[tex]f(x)= x^2+9\\\\for\ each\ x\in R\\\\x^2 \geq 0\ \ \ \Rightarrow\ \ \ x^2+9 \geq 9\ \ \ \Rightarrow\ \ \ f(x) \geq 9\\\\y_{min}=9\\ y_{max}\ \ \ \rightarrow\ \ \ not\ exist[/tex]
Suggested Answer
[tex]a>0 \Rightarrow \hbox{no maximum}[/tex][tex]y_{min}=\frac{-b^2+4ac}{4a}\\y_{min}=\frac{-0^2+4\cdot1\cdot9}{4\cdot1}\\
y_{min}=9[/tex]