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Giải thích các bước giải: a)Gọi M(x;y) $% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqr1ngB % PrgifHhDYfgasaacH8srps0lbbf9q8WrFfeuY-Hhbbf9v8qqaqFr0x % c9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8fr % Fve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakqaabeqaam % aaFiaabaGaamyqaiaadkeaaiaawEniaiabg2da9iaacIcacqGHsisl % caaI0aGaaiilaiaaiodacaGGPaGaai4oamaaFiaabaGaamyqaiaado % eaaiaawEniaiaacIcacqGHsislcaaIZaGaaiilaiaaiwdacaGGPaGa % aiilamaaFiaabaGaam4qaiaad2eaaiaawEniaiabg2da9iaacIcaca % WG4bGaai4oaiaadMhacqGHsislcaaIZaGaaiykaaqaamaaFiaabaGa % am4qaiaad2eaaiaawEniaiabg2da9iaaikdadaWhcaqaaiaadgeaca % WGcbaacaGLxdcacqGHsislcaaIZaWaa8HaaeaacaWGbbGaam4qaaGa % ay51GaaabaGaeyi1HSTaamiEaiabg2da9iaaikdacaGGUaGaaiikai % abgkHiTiaaisdacaGGPaGaeyOeI0IaaG4maiaac6cacaGGOaGaeyOe % I0IaaG4maiaacMcaaeaacaWG2bGaamyyaiaadMhacqGHsislcaaIZa % Gaeyypa0JaaGOmaiaac6cacaaIZaGaeyOeI0IaaG4maiaac6cacaaI % 1aaabaGaeyi1HSTaamiEaiabg2da9iaaigdacaWG2bGaamyyaiaadM % hacqGH9aqpcqGHsislcaaI2aaaaaa!848C! \begin{array}{l} \overrightarrow {AB} = ( - 4,3);\overrightarrow {AC} ( - 3,5),\overrightarrow {CM} = (x;y - 3)\\ \overrightarrow {CM} = 2\overrightarrow {AB} - 3\overrightarrow {AC} \\ \Leftrightarrow x = 2.( - 4) - 3.( - 3)\\ vay - 3 = 2.3 - 3.5\\ \Leftrightarrow x = 1vay = - 6 \end{array}$ Vậy M(1;-6) b)Gọi N(x;y) $% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqr1ngB % PrgifHhDYfgasaacH8srps0lbbf9q8WrFfeuY-Hhbbf9v8qqaqFr0x % c9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8fr % Fve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakqaabeqaam % aaFiaabaGaamyqaiaad6eaaiaawEniaiabg2da9iaacIcacaWG4bGa % eyOeI0IaaG4maiaacUdacaWG5bGaey4kaSIaaGOmaiaacMcacaGGSa % Waa8HaaeaacaWGcbGaamOtaaGaay51GaGaeyypa0JaaiikaiaadIha % cqGHRaWkcaaIXaGaai4oaiaadMhacqGHsislcaaIXaGaaiykaiaacY % cadaWhcaqaaiaadoeacaWGobaacaGLxdcacqGH9aqpcaGGOaGaamiE % aiaacUdacaWG5bGaeyOeI0IaaG4maiaacMcaaeaadaWhcaqaaiaadg % eacaWGobaacaGLxdcacqGHRaWkcaaIYaGaaiOlamaaFiaabaGaamOq % aiaad6eaaiaawEniaiabgkHiTiaaikdadaWhcaqaaiaadoeacaWGob % aacaGLxdcacqGH9aqpdaWhcaqaaiaaicdaaiaawEniaaqaaiabgsDi % BlaadIhacqGHsislcaaIZaGaey4kaSIaaGOmaiaac6cacaGGOaGaam % iEaiabgUcaRiaaigdacaGGPaGaeyOeI0IaaGOmaiaac6cacaWG4bGa % eyypa0JaaGimaaqaaiaadAhacaWGHbGaamyEaiabgUcaRiaaikdacq % GHRaWkcaaIYaGaaiOlaiaacIcacaWG5bGaeyOeI0IaaGOmaiaacMca % cqGHsislcaaIYaGaaiOlaiaacIcacaWG5bGaeyOeI0IaaG4maiaacM % cacqGH9aqpcaaIWaaabaGaeyi1HSTaamiEaiabg2da9iaaigdaaeaa % caWG5bGaeyypa0JaeyOeI0IaaGinaaaaaa!97E6! \begin{array}{l} \overrightarrow {AN} = (x - 3;y + 2),\overrightarrow {BN} = (x + 1;y - 1),\overrightarrow {CN} = (x;y - 3)\\ \overrightarrow {AN} + 2.\overrightarrow {BN} - 2\overrightarrow {CN} = \overrightarrow 0 \\ \Leftrightarrow x - 3 + 2.(x + 1) - 2.x = 0\\ vay + 2 + 2.(y - 2) - 2.(y - 3) = 0\\ \Leftrightarrow x = 1\\ y = - 4 \end{array}$ Vậy N(1;-4)