Biết rằng \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEaiaadw % gadaahaaWcbeqaaiaadIhaaaaaaa!3905! x{e^x}\) là một nguyên hàm của hàm số f(-x) trên khoảng \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaacq % GHsislcqGHEisPcaGG7aGaey4kaSIaeyOhIukacaGLOaGaayzkaaaa % aa!3CED! \left( { - \infty ; + \infty } \right)\). Gọi F(x) là một nguyên hàm của \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOzaiaacE % cadaqadaqaaiaadIhaaiaawIcacaGLPaaacaWGLbWaaWbaaSqabeaa % caWG4baaaaaa!3C24! f'\left( x \right){e^x}\) thỏa mãn F(0) = 1, giá trị của F(-1) bằng:
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Lời giải:
Báo saiVì \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEaiaadw % gadaahaaWcbeqaaiaadIhaaaaaaa!3905! x{e^x}\) là một nguyên hàm của hàm số f(-x) nên \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaaca % WG4bGaamyzamaaCaaaleqabaGaamiEaaaaaOGaayjkaiaawMcaaiaa % cEcacqGH9aqpcaWGMbWaaeWaaeaacqGHsislcaWG4baacaGLOaGaay % zkaaaaaa!40A7! \left( {x{e^x}} \right)' = f\left( { - x} \right)\)\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyi1HSTaam % OzamaabmaabaGaeyOeI0IaamiEaaGaayjkaiaawMcaaiabg2da9iaa % dwgadaahaaWcbeqaaiaadIhaaaGccqGHRaWkcaWG4bGaamyzamaaCa % aaleqabaGaamiEaaaakiabg2da9iaadwgadaahaaWcbeqaaiaadIha % aaGcdaqadaqaaiaaigdacqGHRaWkcaWG4baacaGLOaGaayzkaaaaaa!4B16! \Leftrightarrow f\left( { - x} \right) = {e^x} + x{e^x} = {e^x}\left( {1 + x} \right)\)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyO0H4Taam % OzamaabmaabaGaamiEaaGaayjkaiaawMcaaiabg2da9iaadwgadaah % aaWcbeqaaiabgkHiTiaadIhaaaGcdaqadaqaaiaaigdacqGHsislca % WG4baacaGLOaGaayzkaaaaaa!4401! \Rightarrow f\left( x \right) = {e^{ - x}}\left( {1 - x} \right)\)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyO0H4Taam % OzaiaacEcadaqadaqaaiaadIhaaiaawIcacaGLPaaacqGH9aqpcqGH % sislcaWGLbWaaWbaaSqabeaacqGHsislcaWG4baaaOWaaeWaaeaaca % aIXaGaeyOeI0IaamiEaaGaayjkaiaawMcaaiabgkHiTiaadwgadaah % aaWcbeqaaiabgkHiTiaadIhaaaGccqGH9aqpcqGHsislcaWGLbWaaW % baaSqabeaacqGHsislcaWG4baaaOWaaeWaaeaacaaIYaGaeyOeI0Ia % amiEaaGaayjkaiaawMcaaiabg2da9maabmaabaGaamiEaiabgkHiTi % aaikdaaiaawIcacaGLPaaacaWGLbWaaWbaaSqabeaacqGHsislcaWG % 4baaaaaa!5AF4! \Rightarrow f'\left( x \right) = - {e^{ - x}}\left( {1 - x} \right) - {e^{ - x}} = - {e^{ - x}}\left( {2 - x} \right) = \left( {x - 2} \right){e^{ - x}}\)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacqGHsh % I3caWGMbGaai4jamaabmaabaGaamiEaaGaayjkaiaawMcaaiaadwga % daahaaWcbeqaaiaadIhaaaGccqGH9aqpdaqadaqaaiaadIhacqGHsi % slcaaIYaaacaGLOaGaayzkaaGaamyzamaaCaaaleqabaGaeyOeI0Ia % amiEaaaakiaac6cacaWGLbWaaWbaaSqabeaacaWG4baaaOGaeyypa0 % JaamiEaiabgkHiTiaaikdaaeaacqGHshI3caWGgbWaaeWaaeaacaWG % 4baacaGLOaGaayzkaaGaeyypa0Zaa8qaaeaacaWGMbWaaeWaaeaaca % WG4baacaGLOaGaayzkaaGaamizaiaadIhacqGH9aqpdaWdbaqaamaa % bmaabaGaamiEaiabgkHiTiaaikdaaiaawIcacaGLPaaacaWGKbGaam % iEaiabg2da9maalaaabaGaamiEamaaCaaaleqabaGaaGOmaaaaaOqa % aiaaikdaaaGaeyOeI0IaaGOmaiaadIhacqGHRaWkcaWGdbaaleqabe % qdcqGHRiI8aaWcbeqab0Gaey4kIipaaOqaaiaadAeadaqadaqaaiaa % icdaaiaawIcacaGLPaaacqGH9aqpcaaIXaGaeyO0H4Taam4qaiabg2 % da9iaaigdacqGHshI3caWGgbWaaeWaaeaacaWG4baacaGLOaGaayzk % aaGaeyypa0ZaaSaaaeaacaWG4bWaaWbaaSqabeaacaaIYaaaaaGcba % GaaGOmaaaacqGHsislcaaIYaGaamiEaiabgUcaRiaaigdaaeaacqGH % shI3caWGgbWaaeWaaeaacqGHsislcaaIXaaacaGLOaGaayzkaaGaey % ypa0ZaaSaaaeaadaqadaqaaiabgkHiTiaaigdaaiaawIcacaGLPaaa % daahaaWcbeqaaiaaikdaaaaakeaacaaIYaaaaiabgkHiTiaaikdada % qadaqaaiabgkHiTiaaigdaaiaawIcacaGLPaaacqGHRaWkcaaIXaGa % eyypa0ZaaSaaaeaacaaI3aaabaGaaGOmaaaaaaaa!9949! \begin{array}{l} \Rightarrow f'\left( x \right){e^x} = \left( {x - 2} \right){e^{ - x}}.{e^x} = x - 2\\ \Rightarrow F\left( x \right) = \int {f\left( x \right)dx = \int {\left( {x - 2} \right)dx = \frac{{{x^2}}}{2} - 2x + C} } \\ F\left( 0 \right) = 1 \Rightarrow C = 1 \Rightarrow F\left( x \right) = \frac{{{x^2}}}{2} - 2x + 1\\ \Rightarrow F\left( { - 1} \right) = \frac{{{{\left( { - 1} \right)}^2}}}{2} - 2\left( { - 1} \right) + 1 = \frac{7}{2} \end{array}\)
Đề thi thử tốt nghiệp THPT QG môn Toán năm 2020
Tuyển chọn số 4