Cho hàm số y = f(x) có đạo hàm liên tục trên [0;1] thỏa mãn \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaace % WGMbGbauaadaqadaqaaiaadIhaaiaawIcacaGLPaaaaiaawIcacaGL % PaaadaahaaWcbeqaaiaaikdaaaGccqGHRaWkcaaI0aGaamOzamaabm % aabaGaamiEaaGaayjkaiaawMcaaiabg2da9iaaiIdacaWG4bWaaWba % aSqabeaacaaIYaaaaOGaey4kaSIaaGinaiaacYcacqGHaiIicaWG4b % GaeyicI48aamWaaeaacaaIWaGaai4oaiaaigdaaiaawUfacaGLDbaa % aaa!4E7C! {\left( {f'\left( x \right)} \right)^2} + 4f\left( x \right) = 8{x^2} + 4,\forall x \in \left[ {0;1} \right]\) và f(1) = 2 . Tính \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qCaeaada % WadaqaaiaadAgadaqadaqaaiaadIhaaiaawIcacaGLPaaacqGHRaWk % caWG4baacaGLBbGaayzxaaGaamizaiaadIhaaSqaaiaaicdaaeaaca % aIXaaaniabgUIiYdaaaa!42F9! \int\limits_0^1 {\left[ {f\left( x \right) + x} \right]dx} \).
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Lời giải:
Báo saiĐặt \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOzamaabm % aabaGaamiEaaGaayjkaiaawMcaaiabg2da9iaadggacaWG4bWaaWba % aSqabeaacaaIYaaaaOGaey4kaSIaamOyaiaadIhacqGHRaWkcaWGJb % GaeyO0H4TabmOzayaafaWaaeWaaeaacaWG4baacaGLOaGaayzkaaGa % eyypa0JaaGOmaiaadggacaWG4bGaey4kaSIaamOyaaaa!4D18! f\left( x \right) = a{x^2} + bx + c \Rightarrow f'\left( x \right) = 2ax + b\)
Do đó giả thiết \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyi1HS9aae % WaaeaacaaIYaGaamyyaiaadIhacqGHRaWkcaWGIbaacaGLOaGaayzk % aaWaaWbaaSqabeaacaaIYaaaaOGaey4kaSIaaGinaiaadggacaWG4b % WaaWbaaSqabeaacaaIYaaaaOGaey4kaSIaaGinaiaadkgacaWG4bGa % ey4kaSIaaGinaiaadogacqGH9aqpcaaI4aGaamiEamaaCaaaleqaba % GaaGOmaaaakiabgUcaRiaaisdaaaa!4F0D! \Leftrightarrow {\left( {2ax + b} \right)^2} + 4a{x^2} + 4bx + 4c = 8{x^2} + 4\)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyi1HS9aae % WaaeaacaaI0aGaamyyamaaCaaaleqabaGaaGOmaaaakiabgUcaRiaa % isdacaWGHbaacaGLOaGaayzkaaGaamiEamaaCaaaleqabaGaaGOmaa % aakiabgUcaRmaabmaabaGaaGinaiaadggacaWGIbGaey4kaSIaaGin % aiaadkgaaiaawIcacaGLPaaacaWG4bGaey4kaSIaamOyamaaCaaale % qabaGaaGOmaaaakiabgUcaRiaaisdacaWGJbGaeyypa0JaaGioaiaa % dIhadaahaaWcbeqaaiaaikdaaaGccqGHRaWkcaaI0aaaaa!53FB! \Leftrightarrow \left( {4{a^2} + 4a} \right){x^2} + \left( {4ab + 4b} \right)x + {b^2} + 4c = 8{x^2} + 4\)
Suy ra \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaiqaaqaabe % qaaiaaisdacaWGHbWaaWbaaSqabeaacaaIYaaaaOGaey4kaSIaaGin % aiaadggacqGH9aqpcaaI4aaabaGaaGinaiaadggacaWGIbGaey4kaS % IaaGinaiaadkgacqGH9aqpcaaIWaaabaGaamOyamaaCaaaleqabaGa % aGOmaaaakiabgUcaRiaaisdacaWGJbGaeyypa0JaaGinaaaacaGL7b % aacqGHuhY2daGabaabaeqabaGaamyyaiabg2da9iaaigdaaeaacaWG % IbGaeyypa0JaaGimaaqaaiaadogacqGH9aqpcaaIXaaaaiaawUhaai % abgkDiElaadAgadaqadaqaaiaadIhaaiaawIcacaGLPaaacqGH9aqp % caWG4bWaaWbaaSqabeaacaaIYaaaaOGaey4kaSIaaGymaaaa!60C8! \left\{ \begin{array}{l} 4{a^2} + 4a = 8\\ 4ab + 4b = 0\\ {b^2} + 4c = 4 \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l} a = 1\\ b = 0\\ c = 1 \end{array} \right. \Rightarrow f\left( x \right) = {x^2} + 1\). Vậy \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qCaeaada % WadaqaaiaadAgadaqadaqaaiaadIhaaiaawIcacaGLPaaacqGHRaWk % caWG4baacaGLBbGaayzxaaGaamizaiaadIhaaSqaaiaaicdaaeaaca % aIXaaaniabgUIiYdGccqGH9aqpdaWcaaqaaiaaiwdaaeaacaaI2aaa % aaaa!4598! \int\limits_0^1 {\left[ {f\left( x \right) + x} \right]dx} = \frac{5}{6}\).
Đề thi thử tốt nghiệp THPT QG môn Toán năm 2020
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