Question

Fungsi f(x) = x3 - 6x2 - 15 x - 8 akan turun interval

Answer 1

Syarat fungsi turun :
f'(x)<0
=> x^3 - 6x^2 - 15x - 8
f'(x) = 3x^2 - 12x - 15
=> dibagi 3
=> x^2 - 4x - 5
( x+1) (x-5)
=> -1 < x < 5

smga bermanfaat!!