Answer:
A. [tex] \cos \: x - 4 \: \cos \: x \: { \sin}^{2}x[/tex] (first option)
Step-by-step explanation:
➡️ [tex] \cos(x + 2x) [/tex]
➡️ [tex] \cos \: x \: { \cos}^{2} x - \sin \: x \: { \sin }^{2} x[/tex]
➡️ [tex] \cos \: x(1 - 2 \sin^{2}x) - \sin \: x \times 2 \sin(x) \cos(x) [/tex]
➡️ [tex] \cos(x) - 2 \sin^{2} x \cos(x) - 2 \sin^{2} x \cos(x) [/tex]
➡️ [tex] \cos(x) - 4 \cos(x) \sin^{2} x[/tex]
