Question

Если f (x) = ctgx-cosx, то f '(x) = 0 - неравенство.

Answer 1

(ctg(x))'=-1/sin^2(x)
cos(x)=-sin(x)
f'(x)=(-1/sin^2(x))+sin(x)=(sin^3(x)-1)/sin^2(x)
f'(x) не равно 0