Question

Найти: Производную f(x), если f(x) = cosx/3, найти f(0), и f штрих (0)

Answer 1

$\bf\displaystyle f(x)=\frac{cosx}{3}=\frac{1}{3}\cdot cosx\\\\f(0)=\frac{1}{3}\cdot cos0=\frac{1}{3}\cdot 1=\frac{1}{3}\\\\\\\\f'(x)=\frac{1}{3}\cdot (-sinx)=-\frac{1}{3}\cdot sinx\\\\f(0)=-\frac{1}{3}\cdot sin0=0$