Suatu fungsi kuadrat melalui titik (0,-3), (1,-2) dan (2,3) maka rumus fungsi kuadrat tersebut adalah...

bentuk umum fungsi kuadrat :
f (x) = ax² + bx + c
f(0) = 2a(0)² + b(0) + c = 2c = 2
f (-1) = 0a(-1)² + b(-1) + 2 = 0a - b + 2 = 0a - b = -2
f (1) = 3a(1) + b(1) + 2 = 3a + b + 2= 3a + b = 3 - 2a + b = 1
gunakan eliminasi
a + b = 1a - b = -2 -2b = 3b = 3/2
a + b = 1a + 3/2 = 2/2a = 2/2 - 3/2a = -1/2
f (x) = ax² + bx + cf (x) = -1/2x² + 3/2x + 2
y = -1/2x² + 3/2x +2