Question

Найти третью производную от

Answer 1

$\displaystyle\\f(x)=3\cos(3x)\\\\f'(x)=3*(3*(-\sin(3x))=-9\sin(3x)\\\\f''(x)=-9*(3*\cos(3x))=-27\cos(3x)\\\\f'''(x)=-27*(3*(-\sin(3x))=81\sin(3x)$