[tex]\it f(x)=ax^2+bx+c \Rightarrow\ V\Big(-\dfrac{b}{2a},\ -\dfrac{\Delta}{4a}\Big)\ -\ v\hat arful\ parabolei[/tex]
Ordonata vârfului se poate determina și calculând
[tex]\it f\Big(-\dfrac{b}{2a}\Big)[/tex]
[tex]\it \ell)\ f(x)=x^2+2x-8\\ \\ \begin{cases} \it -\dfrac{b}{2a}=-\dfrac{2}{2}=-1\\ \\ \it f(-1)=1-2-8=-9 \end{cases} \Rightarrow V(-1,\ -9)[/tex]
[tex]\it k)\ \ f(x)=x^2-7x+6\\ \\ \begin{cases}\it -\dfrac{b}{2a}=-\dfrac{-7}{2}=3,5\\ \\ \it f(3,5)=12,25-24,5+6=-6,25\end{cases} \Rightarrow V(3,5;\ -6,25)[/tex]
[tex]\it g)\ \ f(x)=x^2+14x+48\\ \\ \begin{cases} \it -\dfrac{b}{2a}=-\dfrac{14}{2}=-7\\ \\ \it f(-7)=49-98+48=-1\end{cases} \Rightarrow V(-7,\ -1)[/tex]
