[tex]let \: f(x) = ax {}^{2} + bx + c \\ thus \: f(x) \: represents \: a \: parabola \: whose \: axis \: is \: parallel \: to \: the \: y \: axis \: and \: vertex \: is \: \frac{ - b}{2a} ,\frac{ - d}{4a} \\ [/tex]
At the respective max and min values
