Resposta :
F'(x) = (3x + cos x)' . (2 - sen x) + (3x + cos x) . (2 - sen x)'
F'(x) = (3 - sen x) . (2 - sen x) + (3x + cos x) . ( - cos x)
F'(x) = 6 - 5 . sen x + sen² x - 3x . cos x - cos ² x
F'(x) = (3 - sen x) . (2 - sen x) + (3x + cos x) . ( - cos x)
F'(x) = 6 - 5 . sen x + sen² x - 3x . cos x - cos ² x