Xét hàm số \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEaiabg2 % da9iaadAgadaqadaqaaiaadIhaaiaawIcacaGLPaaacqGH9aqpdaGc % aaqaaiaaigdacqGHRaWkciGGJbGaai4BaiaacohadaahaaWcbeqaai % aaikdaaaGccaaIYaGaamiEaaWcbeaaaaa!43A6! y = f\left( x \right) = \sqrt {1 + {{\cos }^2}2x} \). Chọn câu đúng:
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Lời giải:
Báo saita có \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeizaiaadM % hacqGH9aqpceWGMbGbauaadaqadaqaaiaadIhaaiaawIcacaGLPaaa % caqGKbGaamiEaaaa!3E40! {\rm{d}}y = f'\left( x \right){\rm{d}}x\) \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0ZaaS % aaaeaadaqadaqaaiaaigdacqGHRaWkciGGJbGaai4Baiaacohadaah % aaWcbeqaaiaaikdaaaGccaaIYaGaamiEaaGaayjkaiaawMcaamaaCa % aaleqabaGccWaGGBOmGikaaaqaaiaaikdadaGcaaqaaiaaigdacqGH % RaWkciGGJbGaai4BaiaacohadaahaaWcbeqaaiaaikdaaaGccaaIYa % GaamiEaaWcbeaaaaGccaqGKbGaamiEaaaa!4CAF! = \frac{{{{\left( {1 + {{\cos }^2}2x} \right)}^\prime }}}{{2\sqrt {1 + {{\cos }^2}2x} }}{\rm{d}}x\) \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0ZaaS % aaaeaacqGHsislcaaI0aGaci4yaiaac+gacaGGZbGaaGOmaiaadIha % caGGUaGaci4CaiaacMgacaGGUbGaaGOmaiaadIhaaeaacaaIYaWaaO % aaaeaacaaIXaGaey4kaSIaci4yaiaac+gacaGGZbWaaWbaaSqabeaa % caaIYaaaaOGaaGOmaiaadIhaaSqabaaaaOGaaeizaiaadIhaaaa!4C65! = \frac{{ - 4\cos 2x.\sin 2x}}{{2\sqrt {1 + {{\cos }^2}2x} }}{\rm{d}}x\) \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0ZaaS % aaaeaacqGHsislciGGZbGaaiyAaiaac6gacaaI0aGaamiEaaqaamaa % kaaabaGaaGymaiabgUcaRiGacogacaGGVbGaai4CamaaCaaaleqaba % GaaGOmaaaakiaaikdacaWG4baaleqaaaaakiaabsgacaWG4baaaa!45AF! = \frac{{ - \sin 4x}}{{\sqrt {1 + {{\cos }^2}2x} }}{\rm{d}}x\)