tolongiiinnnn donngg ಥ_ಥ

jawab

lim(x->0)  - (cos 3x - cos x)/(1 - cos x) 

= - {- 2 sin 2x. sin x } / ( 1 - (1 - 2 sin^1/2 x))

= 2 sin 2x sin x / 2 sin² 1/2 x

= 2 (2x)(x) / 2 (1/2 x)(1/2 x)

= 4 x² / (1/2)x²

= 4/(1/2)

= 8