16. Найти f′(1/9), если f(x)=4√x+1/(10x).

\(f'(x)=\frac{2}{\sqrt{x}}-\frac{1}{10x^2}\).

При \(x=\frac19\): \(f'(\frac19)=\frac{2}{1/3}-\frac{1}{10/81}=6-\frac{81}{10}=-\frac{21}{10}\).

Ответ: \(f'(1/9)=-\frac{21}{10}\).