Network
Jadi bentuk fungsi dari f(x) = ax2 + bx + c adalah
f(x) = ax2 – 4ax + 4
f(x) = (-1)x2 – 4(-1)x + 4
f(x) = -x2 + 4x + 4
5. Fungsi kuadrat yang grafiknya melalui (12, 0), (0, 3), dan (0, –2) maka:
x = a(y – y1) (y – y2)
x = a(y – 3) (y – (-2))
x = a(y – 3) (y + 2)
12 = a (0 – 3) (0 + 2)
12 = a (-3) 2
12 = -6a
a = -2
Jadi
x = a(y -3) + (y + 2)
x = -2 (y – 3) (y + 2)
x = -2 (y2 + 2y – 3y – 6)
x = -2 (y2 – y – 6)
x = -2y2 + 2y + 12
6. DIketahui f(x) = ax2 + bx + c
Maka a.02 + b.0 + c = p
c = ax2 + bx + p
Jika grafik melalui (p, 0) dan (–p, 0), maka f(p) = 0 dan f( -p) = 0
f(p) = ap2 + bp + p = 0
= ap + b + 1 = 0
= ap – b + 1 = 0
2b = 0
b = 0
dan
ap2 – bp + p = 0
ap – b + 1 = 0
ap + 1 = 0
a = -1/p
