jika (x)=x2-2x-2 dan f(a)=78 maka nilai a=

f(x) = x² - 2x -2
f(a) = a² - 2a -2 = 78
a² - 2a - 80 = 0

a¹'² = (2±√4+320)/2 = (2±18)/2
a¹ = (2+18)/2 = 10
a² = (2-18)/2 = -8

maka a = -8 atau a = 10