Cho hai số phức \(z_1,z_2\) thỏa mãn \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaqWaaeaaca % WG6bWaaSbaaSqaaiaaigdaaeqaaOGaey4kaSIaaGOmaiabgUcaRiaa % iodacaWGPbaacaGLhWUaayjcSdGaeyypa0JaaGynamaaemaabaGaam % OEamaaBaaaleaacaaIYaaabeaakiabgUcaRiaaikdacqGHRaWkcaaI % ZaGaamyAaaGaay5bSlaawIa7aiabg2da9iaaiodaaaa!4BF6! \left| {{z_1} + 2 + 3i} \right| = 5\left| {{z_2} + 2 + 3i} \right| = 3\). Gọi \(m_0\) là giá trị lớn nhất của phần thực số phức \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca % WG6bWaaSbaaSqaaiaaigdaaeqaaOGaey4kaSIaaGOmaiabgUcaRiaa % iodacaWGPbaabaGaamOEamaaBaaaleaacaaIYaaabeaakiabgUcaRi % aaikdacqGHRaWkcaaIZaGaamyAaaaaaaa!423A! \frac{{{z_1} + 2 + 3i}}{{{z_2} + 2 + 3i}}\). Tìm \(m_0\) .
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Lời giải:
Báo saiTập hợp các điểm \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamytamaaBa % aaleaacaaIXaaabeaakiaacYcacaWGnbWaaSbaaSqaaiaaikdaaeqa % aaaa!3A20! {M_1},{M_2}\) biểu diễn số phức \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOEamaaBa % aaleaacaaIXaaabeaakiaacYcacaWG6bWaaSbaaSqaaiaaikdaaeqa % aaaa!3A7A! {z_1},{z_2}\) là các đường tròn đồng tâm I(-2;-3) , bán kính lần lượt là \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuamaaBa % aaleaacaaIXaaabeaakiabg2da9iaaiodacaGGSaGaamOuamaaBaaa % leaacaaIYaaabeaakiabg2da9maalaaabaGaaG4maaqaaiaaiwdaaa % aaaa!3E89! {R_1} = 3,{R_2} = \frac{3}{5}\).
Đặt \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca % WG6bWaaSbaaSqaaiaaigdaaeqaaOGaey4kaSIaaGOmaiabgUcaRiaa % iodacaWGPbaabaGaamOEamaaBaaaleaacaaIYaaabeaakiabgUcaRi % aaikdacqGHRaWkcaaIZaGaamyAaaaacqGH9aqpcaWG4bGaey4kaSIa % amyEaiaadMgacqGHshI3daabdaqaamaalaaabaGaamOEamaaBaaale % aacaaIXaaabeaakiabgUcaRiaaikdacqGHRaWkcaaIZaGaamyAaaqa % aiaadQhadaWgaaWcbaGaaGOmaaqabaGccqGHRaWkcaaIYaGaey4kaS % IaaG4maiaadMgaaaaacaGLhWUaayjcSdGaeyypa0ZaaqWaaeaacaWG % 4bGaey4kaSIaamyEaiaadMgaaiaawEa7caGLiWoacqGHuhY2daabda % qaamaalaaabaGaamOEamaaBaaaleaacaaIXaaabeaakiabgUcaRiaa % ikdacqGHRaWkcaaIZaGaamyAaaqaaiaadQhadaWgaaWcbaGaaGOmaa % qabaGccqGHRaWkcaaIYaGaey4kaSIaaG4maiaadMgaaaaacaGLhWUa % ayjcSdGaeyypa0ZaaOaaaeaacaWG4bWaaWbaaSqabeaacaaIYaaaaO % Gaey4kaSIaamyEamaaCaaaleqabaGaaGOmaaaaaeqaaOGaeyi1HS9a % aOaaaeaacaWG4bWaaWbaaSqabeaacaaIYaaaaOGaey4kaSIaamyEam % aaCaaaleqabaGaaGOmaaaaaeqaaOGaeyypa0JaaGynaaaa!8156! \frac{{{z_1} + 2 + 3i}}{{{z_2} + 2 + 3i}} = x + yi \Rightarrow \left| {\frac{{{z_1} + 2 + 3i}}{{{z_2} + 2 + 3i}}} \right| = \left| {x + yi} \right| \Leftrightarrow \left| {\frac{{{z_1} + 2 + 3i}}{{{z_2} + 2 + 3i}}} \right| = \sqrt {{x^2} + {y^2}} \Leftrightarrow \sqrt {{x^2} + {y^2}} = 5\)
Do \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEamaaCa % aaleqabaGaaGOmaaaakiabgwMiZkaaicdacqGHshI3caWG4bWaaWba % aSqabeaacaaIYaaaaOGaeyizImQaaGOmaiaaiwdacqGHshI3caWG4b % GaeyizImQaaGynaaaa!47AF! {y^2} \ge 0 \Rightarrow {x^2} \le 25 \Rightarrow x \le 5\). Dấu bằng xảy ra \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca % WG6bWaaSbaaSqaaiaaigdaaeqaaOGaey4kaSIaaGOmaiabgUcaRiaa % iodacaWGPbaabaGaamOEamaaBaaaleaacaaIYaaabeaakiabgUcaRi % aaikdacqGHRaWkcaaIZaGaamyAaaaacqGH9aqpcaaI1aaaaa!43FF! \frac{{{z_1} + 2 + 3i}}{{{z_2} + 2 + 3i}} = 5\).
Vậy \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyBamaaBa % aaleaacaaIWaaabeaakiabg2da9iaaiwdacqGHuhY2daWhcaqaaiaa % dMeacaWGnbWaaSbaaSqaaiaaigdaaeqaaaGccaGLxdcaaaa!403B! {m_0} = 5 \Leftrightarrow \overrightarrow {I{M_1}} \) và \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8Haaeaaca % WGjbGaamytamaaBaaaleaacaaIYaaabeaaaOGaay51Gaaaaa!3A39! \overrightarrow {I{M_2}} \) là hai vecto cùng hướng.
Đề thi thử tốt nghiệp THPT QG môn Toán năm 2020
Tuyển chọn số 5