Biết \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qCaeaaca % WG4bGaaeyzamaaCaaaleqabaGaaGOmaiaadIhaaaGccaWGKbGaamiE % aaWcbaGaaGimaaqaaiaaigdaa0Gaey4kIipakiabg2da9iaadggaca % qGLbWaaWbaaSqabeaacaaIYaaaaOGaey4kaSIaamOyaaaa!4527! \int\limits_0^1 {x{{\rm{e}}^{2x}}dx} = a{{\rm{e}}^2} + b\)\(; ( a,b \in Q)\). Tính P = a + b

Xét \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qCaeaaca % WG4bGaaeyzamaaCaaaleqabaGaaGOmaiaadIhaaaGccaWGKbGaamiE % aaWcbaGaaGimaaqaaiaaigdaa0Gaey4kIipaaaa!3F8D! \int\limits_0^1 {x{{\rm{e}}^{2x}}dx} \). Đặt \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaiqaaqaabe % qaaiaadIhacqGH9aqpcaWG1baabaGaaeyzamaaCaaaleqabaGaaGOm % aiaadIhaaaGccaWGKbGaamiEaiabg2da9iaabsgacaWG2baaaiaawU % haaiabgkDiEpaaceaaeaqabeaacaqGKbGaamiEaiabg2da9iaabsga % caWG1baabaWaaSaaaeaacaaIXaaabaGaaGOmaaaacaqGLbWaaWbaaS % qabeaacaaIYaGaamiEaaaakiabg2da9iaadAhaaaGaay5Eaaaaaa!5061! \left\{ \begin{array}{l} x = u\\ {{\rm{e}}^{2x}}dx = {\rm{d}}v \end{array} \right. \Rightarrow \left\{ \begin{array}{l} {\rm{d}}x = {\rm{d}}u\\ \frac{1}{2}{{\rm{e}}^{2x}} = v \end{array} \right.\)

Khi đó \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qCaeaaca % WG4bGaaeyzamaaCaaaleqabaGaaGOmaiaadIhaaaGccaWGKbGaamiE % aaWcbaGaaGimaaqaaiaaigdaa0Gaey4kIipaaaa!3F8D! \int\limits_0^1 {x{{\rm{e}}^{2x}}dx} \)\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0Zaaq % GaaeaadaWcaaqaaiaaigdaaeaacaaIYaaaaiaadIhacaqGLbWaaWba % aSqabeaacaaIYaGaamiEaaaaaOGaayjcSdWaa0baaSqaaiaaicdaae % aacaaIXaaaaOGaeyOeI0YaaSaaaeaacaaIXaaabaGaaGOmaaaadaWd % XbqaaiaabwgadaahaaWcbeqaaiaaikdacaWG4baaaOGaamizaiaadI % haaSqaaiaaicdaaeaacaaIXaaaniabgUIiYdaaaa!4AA8! = \left. {\frac{1}{2}x{{\rm{e}}^{2x}}} \right|_0^1 - \frac{1}{2}\int\limits_0^1 {{{\rm{e}}^{2x}}dx} \)\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0ZaaS % aaaeaacaaIXaaabaGaaGOmaaaacaqGLbWaaWbaaSqabeaacaaIYaaa % aOGaeyOeI0YaaqGaaeaadaWcaaqaaiaaigdaaeaacaaI0aaaaiaabw % gadaahaaWcbeqaaiaaikdacaWG4baaaaGccaGLiWoadaqhaaWcbaGa % aGimaaqaaiaaigdaaaaaaa!42E2! = \frac{1}{2}{{\rm{e}}^2} - \left. {\frac{1}{4}{{\rm{e}}^{2x}}} \right|_0^1\)\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0ZaaS % aaaeaacaaIXaaabaGaaGOmaaaacaqGLbWaaWbaaSqabeaacaaIYaaa % aOGaeyOeI0YaaSaaaeaacaaIXaaabaGaaGinaaaacaqGLbWaaWbaaS % qabeaacaaIYaaaaOGaey4kaSYaaSaaaeaacaaIXaaabaGaaGinaaaa % aaa!4118! = \frac{1}{2}{{\rm{e}}^2} - \frac{1}{4}{{\rm{e}}^2} + \frac{1}{4}\) \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyypa0ZaaS % aaaeaacaaIXaaabaGaaGinaaaacaqGLbWaaWbaaSqabeaacaaIYaaa % aOGaey4kaSYaaSaaaeaacaaIXaaabaGaaGinaaaaaaa!3CC9! = \frac{1}{4}{{\rm{e}}^2} + \frac{1}{4}\)

suy ra \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyyaiabg2 % da9maalaaabaGaaGymaaqaaiaaisdaaaaaaa!3969! a =b= \frac{1}{4}\). Vậy \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaiabg2 % da9maalaaabaGaaGymaaqaaiaaikdaaaaaaa!3956! P = \frac{1}{2}\)