persamaan fungsi kuadrat yang memotong sumbu x di titik (3,0) dan (5,0) serta melalui titik (2,3)...

(3,0) (5,0)
y = a (x-x1) (x-x2)
= a (x-3)(x-5)

(2,3)
3 = a (2-3)(2-5)
= a(-1)(-3)
3 = 3a
a = 1

y = 1 (x-3)(x-5)
= x²-5x-3x+15
= x²-8x+15