Hàm số \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEaiabg2 % da9iaadAgadaqadaqaaiaadIhaaiaawIcacaGLPaaacqGH9aqpdaWc % aaqaaiaaikdaaeaaciGGJbGaai4Baiaacshadaqadaqaaiabec8aWj % aadIhaaiaawIcacaGLPaaaaaaaaa!4451! y = f\left( x \right) = \frac{2}{{\cot \left( {\pi x} \right)}}\) có f'(3) bằng
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Lời giải:
Báo sai\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmOzayaafa % WaaeWaaeaacaWG4baacaGLOaGaayzkaaGaeyypa0JaeyOeI0YaaSaa % aeaacaaIYaWaamWaaeaaciGGJbGaai4Baiaacshadaqadaqaaiabec % 8aWjaadIhaaiaawIcacaGLPaaaaiaawUfacaGLDbaadaahaaWcbeqa % aOGamai4gkdiIcaaaeaaciGGJbGaai4BaiaacshadaahaaWcbeqaai % aaikdaaaGcdaqadaqaaiabec8aWjaadIhaaiaawIcacaGLPaaaaaGa % eyypa0JaaGOmaiabec8aWnaalaaabaGaaGymaiabgUcaRiGacogaca % GGVbGaaiiDamaaCaaaleqabaGaaGOmaaaakmaabmaabaGaeqiWdaNa % amiEaaGaayjkaiaawMcaaaqaaiGacogacaGGVbGaaiiDamaaCaaale % qabaGaaGOmaaaakmaabmaabaGaeqiWdaNaamiEaaGaayjkaiaawMca % aaaaaaa!65A1! f'\left( x \right) = - \frac{{2{{\left[ {\cot \left( {\pi x} \right)} \right]}^\prime }}}{{{{\cot }^2}\left( {\pi x} \right)}} = 2\pi \frac{{1 + {{\cot }^2}\left( {\pi x} \right)}}{{{{\cot }^2}\left( {\pi x} \right)}}\) \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyO0H4Tabm % OzayaafaWaaeWaaeaacaaIZaaacaGLOaGaayzkaaGaeyypa0JaaGOm % aiabec8aWbaa!3F0D! \Rightarrow f'\left( 3 \right) = 2\pi \)