koordinat titik balik fungsi kuadrat f(x)=x²+2x-8

a=1, b=2, c=-8
[tex]x = \frac{ - b}{2a} = \frac{ - 2}{ 2.1} = - 1[/tex]
[tex]y = \frac{ - ( {b}^{2} - 4ac)}{4a} \\ = \frac{ - ( {2}^{2} - 4.1.( - 8)) }{4.1} \\ = \frac{ - (4 + 32)}{4} \\ = \frac{ -36}{4} = - 9[/tex]
maka koordinat titik baliknya di (-1,-9)