Hàm số \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEaiabg2 % da9maalaaabaGaci4yaiaac+gacaGGZbGaamiEaaqaaiaaikdaciGG % ZbGaaiyAaiaac6gadaahaaWcbeqaaiaaikdaaaGccaWG4baaaaaa!415C! y = \frac{{\cos x}}{{2{{\sin }^2}x}}\) có đạo hàm bằng:

\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmyEayaafa % Gaeyypa0ZaaeWaaeaadaWcaaqaaiGacogacaGGVbGaai4CaiaadIha % aeaacaaIYaGaci4CaiaacMgacaGGUbWaaWbaaSqabeaacaaIYaaaaO % GaamiEaaaaaiaawIcacaGLPaaadaahaaWcbeqaaOGamai4gkdiIcaa % cqGH9aqpdaWcaaqaaiGacohacaGGPbGaaiOBamaaCaaaleqabaGaaG % OmaaaakiaadIhadaqadaqaaiGacogacaGGVbGaai4CaiaadIhaaiaa % wIcacaGLPaaadaahaaWcbeqaaOGamai4gkdiIcaacqGHsisldaqada % qaaiGacohacaGGPbGaaiOBamaaCaaaleqabaGaaGOmaaaakiaadIha % aiaawIcacaGLPaaaciGGJbGaai4BaiaacohacaWG4baabaGaaGOmai % GacohacaGGPbGaaiOBamaaCaaaleqabaGaaGinaaaakiaadIhaaaGa % eyypa0ZaaSaaaeaacqGHsislciGGZbGaaiyAaiaac6gadaahaaWcbe % qaaiaaiodaaaGccaWG4bGaeyOeI0IaaGOmaiGacohacaGGPbGaaiOB % aiaadIhaciGGJbGaai4BaiaacohacaWG4bGaci4yaiaac+gacaGGZb % GaamiEaaqaaiaaikdaciGGZbGaaiyAaiaac6gadaahaaWcbeqaaiaa % isdaaaGccaWG4baaaaaa!7E6A! y' = {\left( {\frac{{\cos x}}{{2{{\sin }^2}x}}} \right)^\prime } = \frac{{{{\sin }^2}x{{\left( {\cos x} \right)}^\prime } - \left( {{{\sin }^2}x} \right)\cos x}}{{2{{\sin }^4}x}} = \frac{{ - {{\sin }^3}x - 2\sin x\cos x\cos x}}{{2{{\sin }^4}x}}\)

\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0Jaey % OeI0YaaSaaaeaaciGGZbGaaiyAaiaac6gadaahaaWcbeqaaiaaikda % aaGccaWG4bGaey4kaSIaaGOmaiaabogacaqGVbGaae4CamaaCaaale % qabaGaaGOmaaaakiaadIhaaeaaciGGZbGaaiyAaiaac6gadaahaaWc % beqaaiaaiodaaaGccaWG4baaaiabg2da9iabgkHiTmaalaaabaGaaG % ymaiabgUcaRiaabogacaqGVbGaae4CamaaCaaaleqabaGaaGOmaaaa % kiaadIhaaeaaciGGZbGaaiyAaiaac6gadaahaaWcbeqaaiaaiodaaa % GccaWG4baaaaaa!550B! = - \frac{{{{\sin }^2}x + 2{\rm{co}}{{\rm{s}}^2}x}}{{{{\sin }^3}x}} = - \frac{{1 + {\rm{co}}{{\rm{s}}^2}x}}{{{{\sin }^3}x}}\)