Verified answer

Ответ: F(x)=9*sin(x/3)-1/3*cos(3*x)+C.

Объяснение:

F(x)=3*∫cos(x/3)*dx+∫sin(3*x)*dx=9*∫cos(x/3)*d(x/3)+1/3*∫sin(3*x)*d(3*x)=9*sin(x/3)-1/3*cos(3*x)+C.