Tổng \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamivaiabg2 % da9iaadoeadaqhaaWcbaGaaGOmaiaaicdacaaIXaGaaG4naaqaaiaa % igdaaaGccqGHRaWkcaWGdbWaa0baaSqaaiaaikdacaaIWaGaaGymai % aaiEdaaeaacaaIZaaaaOGaey4kaSIaam4qamaaDaaaleaacaaIYaGa % aGimaiaaigdacaaI3aaabaGaaGynaaaakiabgUcaRiaac6cacaGGUa % GaaiOlaiabgUcaRiaadoeadaqhaaWcbaGaaGOmaiaaicdacaaIXaGa % aG4naaqaaiaaikdacaaIWaGaaGymaiaaiEdaaaaaaa!5254! T = C_{2017}^1 + C_{2017}^3 + C_{2017}^5 + ... + C_{2017}^{2017}\) bằng:
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Lời giải:
Báo saiXét hai khai triển:
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGOmamaaCa % aaleqabaGaaGOmaiaaicdacaaIXaGaaG4naaaakiabg2da9maabmaa % baGaaGymaiabgUcaRiaaigdaaiaawIcacaGLPaaadaahaaWcbeqaai % aaikdacaaIWaGaaGymaiaaiEdaaaGccqGH9aqpcaWGdbWaa0baaSqa % aiaaikdacaaIWaGaaGymaiaaiEdaaeaacaaIWaaaaOGaey4kaSIaam % 4qamaaDaaaleaacaaIYaGaaGimaiaaigdacaaI3aaabaGaaGymaaaa % kiabgUcaRiaadoeadaqhaaWcbaGaaGOmaiaaicdacaaIXaGaaG4naa % qaaiaaikdaaaGccqGHRaWkcaWGdbWaa0baaSqaaiaaikdacaaIWaGa % aGymaiaaiEdaaeaacaaIZaaaaOGaey4kaSIaaiOlaiaac6cacaGGUa % Gaey4kaSIaam4qamaaDaaaleaacaaIYaGaaGimaiaaigdacaaI3aaa % baGaaGOmaiaaicdacaaIXaGaaG4naaaakiaaykW7caaMc8UaaGPaVp % aabmaabaGaaGymaaGaayjkaiaawMcaaaaa!69E9! {2^{2017}} = {\left( {1 + 1} \right)^{2017}} = C_{2017}^0 + C_{2017}^1 + C_{2017}^2 + C_{2017}^3 + ... + C_{2017}^{2017}\,\,\,\left( 1 \right)\)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGimaiabg2 % da9maabmaabaGaaGymaiabgkHiTiaaigdaaiaawIcacaGLPaaadaah % aaWcbeqaaiaaikdacaaIWaGaaGymaiaaiEdaaaGccqGH9aqpcaWGdb % Waa0baaSqaaiaaikdacaaIWaGaaGymaiaaiEdaaeaacaaIWaaaaOGa % eyOeI0Iaam4qamaaDaaaleaacaaIYaGaaGimaiaaigdacaaI3aaaba % GaaGymaaaakiabgUcaRiaadoeadaqhaaWcbaGaaGOmaiaaicdacaaI % XaGaaG4naaqaaiaaikdaaaGccqGHsislcaWGdbWaa0baaSqaaiaaik % dacaaIWaGaaGymaiaaiEdaaeaacaaIZaaaaOGaey4kaSIaaiOlaiaa % c6cacaGGUaGaeyOeI0Iaam4qamaaDaaaleaacaaIYaGaaGimaiaaig % dacaaI3aaabaGaaGOmaiaaicdacaaIXaGaaG4naaaakiaaykW7caaM % c8UaaGPaVlaaykW7daqadaqaaiaaikdaaiaawIcacaGLPaaaaaa!6876! 0 = {\left( {1 - 1} \right)^{2017}} = C_{2017}^0 - C_{2017}^1 + C_{2017}^2 - C_{2017}^3 + ... - C_{2017}^{2017}\,\,\,\,\left( 2 \right)\)
Lấy (1) - (2) theo vế ta được: \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGOmamaaCa % aaleqabaGaaGOmaiaaicdacaaIXaGaaG4naaaakiabg2da9iaaykW7 % caaMc8UaaGPaVlaaikdadaqadaqaaiaadoeadaqhaaWcbaGaaGOmai % aaicdacaaIXaGaaG4naaqaaiaaigdaaaGccqGHRaWkcaWGdbWaa0ba % aSqaaiaaikdacaaIWaGaaGymaiaaiEdaaeaacaaIZaaaaOGaey4kaS % Iaam4qamaaDaaaleaacaaIYaGaaGimaiaaigdacaaI3aaabaGaaGyn % aaaakiabgUcaRiaac6cacaGGUaGaaiOlaiabgUcaRiaadoeadaqhaa % WcbaGaaGOmaiaaicdacaaIXaGaaG4naaqaaiaaikdacaaIWaGaaGym % aiaaiEdaaaaakiaawIcacaGLPaaacqGHshI3caWGubGaeyypa0JaaG % OmamaaCaaaleqabaGaaGOmaiaaicdacaaIXaGaaGOnaaaaaaa!6466! {2^{2017}} = \,\,\,2\left( {C_{2017}^1 + C_{2017}^3 + C_{2017}^5 + ... + C_{2017}^{2017}} \right) \Rightarrow T = {2^{2016}}\)
Đề thi thử tốt nghiệp THPT QG môn Toán năm 2020
Tuyển chọn số 1