Rewrite with only sin x and cos x.

sin 3x - cos x

sin (3 x) - cos (x)=

= sin (2x + x) - cos (x)=

= sin 2x * cos x + cos 2 x * sin x - cos x = ( using additional formulas )

= 2 sin x cos² x + ( cos² x - sin² x ) sin x - cos x =

= 2 sin x cos² x + ( 1 - sin² x - sin² x ) sin x - cos x =

= 2 sin x cos² x + ( 1 - 2 sin² x ) sin x - cos x =

= 2 sin x cos² x + sin x  - 2 sin³ x - cos x

B )

Step-by-step explanation: