fungsi f(x)=x²-2x-8 jika f(p)=-5 nilai P adalah

Mapel : Matematika
Materi : Relasi dan Fungsi

f(x) = x² - 2x - 8

f(p) = -5

Penyelesaian :

x² - 2x - 8 = -5
x² - 2x - 8 + 5 = 0
x² - 2x - 3 = 0

a = 1
b = -2
c = -3

X12 = -b ± √(b² - 4ac) / 2a

X12 = -(-2) ± √[(-2)² - 4(1)(-3)] /2

X12 = 2 ± √[4 + 12] /2

X12 = 2 ± √16 /2

X12 = 2 ± 4 / 2

X12 = 1 ± 2

X1 = 1 + 2 = 3
X2 = 1 - 2 = -1

Jadi P = 3 atau P = -1