Trong khai triển \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaaca % WG4bGaey4kaSYaaSaaaeaacaaI4aaabaGaamiEamaaCaaaleqabaGa % aGOmaaaaaaaakiaawIcacaGLPaaadaahaaWcbeqaaiaaiMdaaaaaaa!3D0D! {\left( {x + \frac{8}{{{x^2}}}} \right)^9}\), số hạng không chứa x là
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Lời giải:
Báo saiTa có \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaaca % WG4bGaey4kaSYaaSaaaeaacaaI4aaabaGaamiEamaaCaaaleqabaGa % aGOmaaaaaaaakiaawIcacaGLPaaadaahaaWcbeqaaiaaiMdaaaGccq % GH9aqpdaaeWbqaaiaadoeadaqhaaWcbaGaaGyoaaqaaiaadUgaaaGc % caGGUaGaamiEamaaCaaaleqabaGaaGyoaiabgkHiTiaadUgaaaGcda % qadaqaamaalaaabaGaaGioaaqaaiaadIhadaahaaWcbeqaaiaaikda % aaaaaaGccaGLOaGaayzkaaWaaWbaaSqabeaacaWGRbaaaaqaaiaadU % gacqGH9aqpcaaIWaaabaGaaGyoaaqdcqGHris5aOGaeyypa0ZaaabC % aeaacaWGdbWaa0baaSqaaiaaiMdaaeaacaWGRbaaaOGaaiOlaiaaiI % dadaahaaWcbeqaaiaadUgaaaGccaGGUaGaamiEamaaCaaaleqabaGa % aGyoaiabgkHiTiaaiodacaWGRbaaaaqaaiaadUgacqGH9aqpcaaIWa % aabaGaaGyoaaqdcqGHris5aaaa!61A7! {\left( {x + \frac{8}{{{x^2}}}} \right)^9} = \sum\limits_{k = 0}^9 {C_9^k.{x^{9 - k}}{{\left( {\frac{8}{{{x^2}}}} \right)}^k}} = \sum\limits_{k = 0}^9 {C_9^k{{.8}^k}.{x^{9 - 3k}}} \)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGyoaiabgk % HiTiaaiodacaWGRbGaeyypa0JaaGimaiabgsDiBlaadUgacqGH9aqp % caaIZaaaaa!401F! 9- 3k = 0 \Leftrightarrow k = 3\) . Số hạng không chứa x là \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaDa % aaleaacaaI5aaabaGaaG4maaaakiaac6cacaaI4aWaaWbaaSqabeaa % caaIZaaaaOGaeyypa0JaaGinaiaaiodacaaIWaGaaGimaiaaiIdaaa % a!3F91! C_9^3{.8^3} = 43008\)
Đề thi thử tốt nghiệp THPT QG môn Toán năm 2020
Tuyển chọn số 5