Question

Найдите значение производной функции f (x)=cos x- 2 sin x при x= -Пи/4

Answer 1

f'(x)= - sin x-2cos x

f'(-π/4)=-sin (-π/4)-2cos(-π/4)=sin(π/4)-2cos(-π/4)=1/√2-2/√2= - 1/√2