Tìm \(\int {\left( {\cos 6x - \cos 4x} \right)dx}...

Câu hỏi: Tìm $\int {\left( {\cos 6x - \cos 4x} \right)dx}$ là:

A. $\frac{1}{6}\sin 6x - \frac{1}{4}\sin 4x + C$

B. $6\sin 6x - 4\sin 4x + C$

C. $- \frac{1}{6}\sin 6x + \frac{1}{4}\sin 4x + C$

D. $- 6\sin 6x + \sin 4x + C$