Có bao nhiêu giá trị nguyên dương của tham số m để tập nghiệm của bất phương trình \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaaca % aIZaWaaWbaaSqabeaacaWG4bGaey4kaSIaaGOmaaaakiabgkHiTmaa % kaaabaGaaG4maaWcbeaaaOGaayjkaiaawMcaamaabmaabaGaaG4mam % aaCaaaleqabaGaamiEaaaakiabgkHiTiaaikdacaWGTbaacaGLOaGa % ayzkaaGaeyipaWJaaGimaaaa!44AD! \left( {{3^{x + 2}} - \sqrt 3 } \right)\left( {{3^x} - 2m} \right) < 0\) chứa không quá 9 số nguyên?
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Lời giải:
Báo saiHD:
Bất phương trình trở thành: \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaaca % aIZaWaaWbaaSqabeaacaWG4bGaey4kaSIaaGOmaaaakiabgkHiTiaa % iodadaahaaWcbeqaamaalaaabaGaaGymaaqaaiaaikdaaaaaaaGcca % GLOaGaayzkaaWaamWaaeaacaaIZaWaaWbaaSqabeaacaWG4baaaOGa % eyOeI0IaaG4mamaaCaaaleqabaGaciiBaiaac+gacaGGNbWaaSbaaW % qaaiaaiodaaeqaaSWaaeWaaeaacaaIYaGaamyBaaGaayjkaiaawMca % aaaaaOGaay5waiaaw2faaiabgYda8iaaicdacqGHuhY2daqadaqaai % aadIhacqGHRaWkdaWcaaqaaiaaiodaaeaacaaIYaaaaaGaayjkaiaa % wMcaamaadmaabaGaamiEaiabgkHiTiGacYgacaGGVbGaai4zamaaBa % aaleaacaaIZaaabeaakmaabmaabaGaaGOmaiaad2gaaiaawIcacaGL % PaaaaiaawUfacaGLDbaacqGH8aapcaaIWaaaaa!60D2! \left( {{3^{x + 2}} - {3^{\frac{1}{2}}}} \right)\left[ {{3^x} - {3^{{{\log }_3}\left( {2m} \right)}}} \right] < 0 \Leftrightarrow \left( {x + \frac{3}{2}} \right)\left[ {x - {{\log }_3}\left( {2m} \right)} \right] < 0\)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyi1HSTaey % OeI0YaaSaaaeaacaaIZaaabaGaaGOmaaaacqGH8aapcaWG4bGaeyip % aWJaciiBaiaac+gacaGGNbWaaSbaaSqaaiaaiodaaeqaaOGaaGOmai % aad2gaaaa!433B! \Leftrightarrow - \frac{3}{2} < x < {\log _3}2m\) mà x nhận tối đa 9 số \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyO0H4Taam % iEaiabg2da9maacmaabaGaeyOeI0IaaGymaiaacUdacaaIWaGaai4o % aiaaigdacaGG7aGaaiOlaiaac6cacaGGUaGaai4oaiaaiEdaaiaawU % hacaGL9baaaaa!4574! \Rightarrow x = \left\{ { - 1;0;1;...;7} \right\}\)
Do đó \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaciiBaiaac+ % gacaGGNbWaaSbaaSqaaiaaiodaaeqaaOWaaeWaaeaacaaIYaGaamyB % aaGaayjkaiaawMcaaiabgYda8iaaiIdacqGHuhY2caWGTbGaeyipaW % ZaaSaaaeaacaaIZaWaaWbaaSqabeaacaaI4aaaaaGcbaGaaGOmaaaa % cqGHijYUcaaIZaGaaGOmaiaaiIdacaaIWaGaaiilaiaaiwdaaaa!4B9C! {\log _3}\left( {2m} \right) < 8 \Leftrightarrow m < \frac{{{3^8}}}{2} \approx 3280,5\)
Đề thi thử tốt nghiệp THPT QG môn Toán năm 2020
Tuyển chọn số 5