F(x) = -2x kuadrat + 11x - 15 =? tentukan Sumbu X,Y dan titik puncak

f(x) = -2x² + 11x - 15

1) titik potong terhadap sumbu x jika y = 0
-2x² + 11x - 15 = 0
2x² - 11x + 15 = 0
(2x - 5)(x - 3) = 0
x = 5/2 = 2 1/2 atau x = 3
(2 1/2, 0) dan (3, 0)

2) titik potong terhadap sumbu y jika x = 0
y = -2(0)² + 11(0) - 15
y = -15
(0, -15)

3) titik puncak
x = -b/(2a) = -11/(2(-2)) = 11/4
D = b² - 4ac = 11² - 4(-2)(-15) = 121 - 120 = 1
y = -D/(4a) = -1/(4(-2)) = 1/8
(11/4, 1/8) = (2 3/4, 1/8)