3.9-bo'lim : Zanjir qoidasi
12. \(V\left( x \right) = \ln \left( {\sin \left( x \right) - \cot \left( x \right)} \right)\) ni farqlang.
Yechim
Ushbu muammo uchun tashqi funktsiya (umid qilamanki) aniq logarifm va ichki funktsiya logarifm ichidagi narsadir. Demak, hosila,
\[V^{\prime}\left( x \right) = \frac{1}{{\sin \left( x \right) - \cot \left( x \right)}}\left( {\cos \left( x \right) + {{\csc }^2}\left( x \right)} \right) = \require{bbox} \bbox[2pt,border:1px solid black]{{\frac{{\cos \left( x \right) + {{\csc }^2}\left( x \right)}}{{\sin \left( x \right) - \cot \left( x \right)}}}}\]Logarifm bilan bog'liq muammolar esda tutingki, logarifmni farqlashdan keyin (i.e. tashqi funktsiya) ichki funktsiyani hosilaga almashtirishingiz kerak. Shunday qilib, shunchaki olish o'rniga,
\[\frac{1}{x}\]biz quyidagilarni olamiz (i.e. biz ichki funktsiyani lotinga joylashtirdik),
\[\frac{1}{{\sin \left( x \right) - \cot \left( x \right)}}\]Keyin, biz, albatta, ichki funktsiyaning hosilasiga ko'paytirishni unuta olmaymiz.