Cho hàm số y = cos3x.sin 2x .Tính \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEaiaacE % cadaqadaqaamaalaaabaGaeqiWdahabaGaaG4maaaaaiaawIcacaGL % Paaaaaa!3BB0! y'\left( {\frac{\pi }{3}} \right)\) bằng
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Lời giải:
Báo sai\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEaiaacE % cacqGH9aqpdaqadaqaaiGacogacaGGVbGaai4CaiaaiodacaWG4baa % caGLOaGaayzkaaGaai4jaiGacohacaGGPbGaaiOBaiaaikdacaGG4b % Gaey4kaSIaci4yaiaac+gacaGGZbGaaG4maiaadIhadaqadaqaaiGa % cohacaGGPbGaaiOBaiaaikdacaGG4baacaGLOaGaayzkaaGaai4jai % abg2da9iabgkHiTiaaiodaciGGZbGaaiyAaiaac6gacaaIZaGaamiE % aiaac6caciGGZbGaaiyAaiaac6gacaaIYaGaamiEaiabgUcaRiaaik % daciGGJbGaai4BaiaacohacaaIZaGaamiEaiaac6caciGGJbGaai4B % aiaacohacaaIYaGaamiEaaaa!6815! y' = \left( {\cos 3x} \right)'\sin 2x + \cos 3x\left( {\sin 2x} \right)' = - 3\sin 3x.\sin 2x + 2\cos 3x.\cos 2x\)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEaiaacE % cadaqadaqaamaalaaabaGaeqiWdahabaGaaG4maaaaaiaawIcacaGL % PaaacqGH9aqpcqGHsislcaaIZaGaci4CaiaacMgacaGGUbGaaG4mam % aalaaabaGaeqiWdahabaGaaG4maaaacaGGUaGaci4CaiaacMgacaGG % UbGaaGOmamaalaaabaGaeqiWdahabaGaaG4maaaacqGHRaWkcaaIYa % Gaci4yaiaac+gacaGGZbGaaG4mamaalaaabaGaeqiWdahabaGaaG4m % aaaacaGGUaGaci4yaiaac+gacaGGZbGaaGOmamaalaaabaGaeqiWda % habaGaaG4maaaacqGH9aqpcaaIXaaaaa!5B93! y'\left( {\frac{\pi }{3}} \right) = - 3\sin 3\frac{\pi }{3}.\sin 2\frac{\pi }{3} + 2\cos 3\frac{\pi }{3}.\cos 2\frac{\pi }{3} = 1\)