Tìm nguyên hàm:

Câu hỏi: Tìm nguyên hàm: $J=\int \left(\cos 3x.\cos 4x+{\sin }^{3}2x\right)dx$

A. $\frac{1}{14}\sin 7x-\frac{1}{2}\sin x-\frac{3}{8}\cos 2x+\frac{1}{24}\cos 6x+C$

B. $\frac{1}{14}\sin 7x+\frac{1}{2}\sin x+\frac{3}{8}\cos 2x+\frac{1}{24}\cos 6x+C$

C. $\frac{1}{14}\sin 7x+\frac{1}{2}\sin x-\frac{3}{8}\cos 2x+\frac{1}{24}\cos 6x+C$

D. $\frac{1}{14}\sin 7x+\frac{1}{2}\sin x-\frac{3}{8}\cos 2x-2\frac{1}{24}\cos 6x+C$