Cho biết \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOramaabm % aabaGaamiEaaGaayjkaiaawMcaaiabg2da9maalaaabaGaaGymaaqa % aiaaiodaaaGaamiEamaaCaaaleqabaGaaG4maaaakiabgUcaRiaaik % dacaWG4bGaeyOeI0YaaSaaaeaacaaIXaaabaGaamiEaaaaaaa!4314! F\left( x \right) = \frac{1}{3}{x^3} + 2x - \frac{1}{x}\) là một nguyên hàm của \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOzamaabm % aabaGaamiEaaGaayjkaiaawMcaaiabg2da9maalaaabaWaaeWaaeaa % caWG4bWaaWbaaSqabeaacaaIYaaaaOGaey4kaSIaamyyaaGaayjkai % aawMcaamaaCaaaleqabaGaaGOmaaaaaOqaaiaadIhadaahaaWcbeqa % aiaaikdaaaaaaaaa!4295! f\left( x \right) = \frac{{{{\left( {{x^2} + a} \right)}^2}}}{{{x^2}}}\). Tìm nguyên hàm của \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4zamaabm % aabaGaamiEaaGaayjkaiaawMcaaiabg2da9iaadIhaciGGJbGaai4B % aiaacohacaWGHbGaamiEaaaa!401F! g\left( x \right) = x\cos ax\)
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Lời giải:
Báo sai\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmOrayaafa % WaaeWaaeaacaWG4baacaGLOaGaayzkaaGaeyypa0JaamiEamaaCaaa % leqabaGaaGOmaaaakiabgUcaRiaaikdacqGHRaWkdaWcaaqaaiaaig % daaeaacaWG4bWaaWbaaSqabeaacaaIYaaaaaaakiabg2da9maalaaa % baWaaeWaaeaacaWG4bWaaWbaaSqabeaacaaIYaaaaOGaey4kaSIaaG % ymaaGaayjkaiaawMcaamaaCaaaleqabaGaaGOmaaaaaOqaaiaadIha % daahaaWcbeqaaiaaikdaaaaaaaaa!4A87! F'\left( x \right) = {x^2} + 2 + \frac{1}{{{x^2}}} = \frac{{{{\left( {{x^2} + 1} \right)}^2}}}{{{x^2}}}\) suy ra a = 1
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qaaeaaca % WGNbWaaeWaaeaacaWG4baacaGLOaGaayzkaaGaaeizaiaadIhaaSqa % beqaniabgUIiYdGccqGH9aqpdaWdbaqaaiaadIhaciGGJbGaai4Bai % aacohacaWG4bGaaeizaiaadIhaaSqabeqaniabgUIiYdGccqGH9aqp % daWdbaqaaiaadIhacaqGKbGaci4CaiaacMgacaGGUbGaamiEaaWcbe % qab0Gaey4kIipakiabg2da9iaadIhacaGGUaGaci4CaiaacMgacaGG % UbGaamiEaiabgkHiTmaapeaabaGaci4CaiaacMgacaGGUbGaamiEai % aabsgacaWG4baaleqabeqdcqGHRiI8aOGaeyypa0JaamiEaiaac6ca % ciGGZbGaaiyAaiaac6gacaWG4bGaey4kaSIaci4yaiaac+gacaGGZb % GaamiEaiabgUcaRiaadoeaaaa!6BEA! \int {g\left( x \right){\rm{d}}x} = \int {x\cos x{\rm{d}}x} = \int {x{\rm{d}}\sin x} = x.\sin x - \int {\sin x{\rm{d}}x} = x.\sin x + \cos x + C\)