Cho hàm số \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEaiabg2 % da9iaadAgacaGGOaGaamiEaiaacMcacqGH9aqpdaWcaaqaaiGacoga % caGGVbGaai4CaiaadIhaaeaacaaIXaGaeyOeI0Iaci4CaiaacMgaca % GGUbGaamiEaaaaaaa!459C! y = f(x) = \frac{{\cos x}}{{1 - \sin x}}\). Giá trị biểu thức \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmOzayaafa % WaaeWaaeaadaWcaaqaaiabec8aWbqaaiaaiAdaaaaacaGLOaGaayzk % aaGaeyOeI0IabmOzayaafaWaaeWaaeaacqGHsisldaWcaaqaaiabec % 8aWbqaaiaaiAdaaaaacaGLOaGaayzkaaaaaa!41E8! f'\left( {\frac{\pi }{6}} \right) - f'\left( { - \frac{\pi }{6}} \right)\) là
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Lời giải:
Báo sai\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmOzayaafa % WaaeWaaeaacaWG4baacaGLOaGaayzkaaGaeyypa0ZaaSaaaeaadaqa % daqaaiGacogacaGGVbGaai4CaiaadIhaaiaawIcacaGLPaaadaahaa % WcbeqaaOGamai4gkdiIcaadaqadaqaaiaaigdacqGHsislciGGZbGa % aeyAaiaab6gacaWG4baacaGLOaGaayzkaaGaeyOeI0Iaaiikaiaaig % dacqGHsislciGGZbGaaeyAaiaab6gacaWG4bGabiykayaafaGaai4y % aiaac+gacaGGZbGaamiEaaqaamaabmaabaGaaGymaiabgkHiTiGaco % hacaqGPbGaaeOBaiaadIhaaiaawIcacaGLPaaadaahaaWcbeqaaiaa % ikdaaaaaaOGaeyypa0ZaaSaaaeaacaaIXaaabaGaaGymaiabgkHiTi % GacohacaqGPbGaaeOBaiaadIhaaaGaeyO0H4TabmOzayaafaWaaeWa % aeaadaWcaaqaaiabec8aWbqaaiaaiAdaaaaacaGLOaGaayzkaaGaey % OeI0IabmOzayaafaWaaeWaaeaacqGHsisldaWcaaqaaiabec8aWbqa % aiaaiAdaaaaacaGLOaGaayzkaaGaeyypa0ZaaSaaaeaacaaI0aaaba % GaaG4maaaaaaa!75C3! f'\left( x \right) = \frac{{{{\left( {\cos x} \right)}^\prime }\left( {1 - {\mathop{\rm s}\nolimits} {\rm{in}}x} \right) - (1 - {\mathop{\rm s}\nolimits} {\rm{in}}x)'cosx}}{{{{\left( {1 - {\mathop{\rm s}\nolimits} {\rm{in}}x} \right)}^2}}} = \frac{1}{{1 - {\mathop{\rm s}\nolimits} {\rm{in}}x}} \Rightarrow f'\left( {\frac{\pi }{6}} \right) - f'\left( { - \frac{\pi }{6}} \right) = \frac{4}{3}\)