Nếu \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmOzayaaga % WaaeWaaeaacaWG4baacaGLOaGaayzkaaGaeyypa0ZaaSaaaeaacaaI % YaGaci4CaiaacMgacaGGUbGaamiEaaqaaiGacogacaGGVbGaai4Cam % aaCaaaleqabaGaaG4maaaakiaadIhaaaaaaa!43DD! f''\left( x \right) = \frac{{2\sin x}}{{{{\cos }^3}x}}\) thì f(x) bằng
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Lời giải:
Báo saiVì \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaaca % GG0bGaaiyyaiaac6gacaWG4baacaGLOaGaayzkaaWaaWbaaSqabeaa % kiadacUHYaIOliaaygW7kiadacUHYaIOaaGaeyypa0ZaaeWaaeaada % WcaaqaaiaaigdaaeaacaqGJbGaae4BaiaabohadaahaaWcbeqaaiaa % ikdaaaGccaWG4baaaaGaayjkaiaawMcaamaaCaaaleqabaGccWaGGB % OmGikaaaaa!4E25! {\left( {tanx} \right)^{\prime \prime }} = {\left( {\frac{1}{{{\rm{co}}{{\rm{s}}^2}x}}} \right)^\prime }\) \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0ZaaS % aaaeaacqGHsislcaaIYaGaae4yaiaab+gacaqGZbGaamiEaiabgwSi % xpaabmaabaGaeyOeI0Iaae4CaiaabMgacaqGUbGaamiEaaGaayjkai % aawMcaaaqaaiaabogacaqGVbGaae4CamaaCaaaleqabaGaaGinaaaa % kiaadIhaaaaaaa!49CD! = \frac{{ - 2{\rm{cos}}x \cdot \left( { - {\rm{sin}}x} \right)}}{{{\rm{co}}{{\rm{s}}^4}x}}\) \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0ZaaS % aaaeaacaaIYaGaae4CaiaabMgacaqGUbGaamiEaaqaaiaabogacaqG % VbGaae4CamaaCaaaleqabaGaaG4maaaakiaadIhaaaaaaa!4054! = \frac{{2{\rm{sin}}x}}{{{\rm{co}}{{\rm{s}}^3}x}}\)