diketahui fungsi f(x)=x2-2x-8. jika f(b)=-5, nilai b=

Kelas 8 Matematika
Bab Fungsi 

f(x) = x² - 2x - 8

f(b) = -5
b² - 2b - 8 = -5
b² - 2b - 8 + 5 = 0
b² - 2b - 3 = 0
(b - 3) (b + 1) = 0
b - 3 = 0
b = 3

b + 1 = 0
b = -1