Plis bantuin jawab ya....

f(x) = ax² + bx + c

puncak (2, 1)
y = a(x - x1)² + y1
y = a(x - 2)² + 1

dan melalui titik (-1, 10)
(10) = a (-1 - 2)² + 1
10 = a (-3)² + 1
10 = 9a + 1
9a = 10 - 1
a = 9/9
a = 1

maka persamaan parabolanya
y = 1 (x - 2)² + 1
y = x² - 4x + 4 + 1
y = x² - 4x + 5
a = 1 ; b = -4 ; c = 5

dit : nilai a + b + c = 1 - 4 + 5 = 2