Số gia của hàm số \(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOzamaabm % aabaGaamiEaaGaayjkaiaawMcaaiabg2da9iaadIhadaahaaWcbeqa % aiaaikdaaaGccqGHsislcaaI0aGaamiEaiabgUcaRiaaigdaaaa!409F! f\left( x \right) = {x^2} - 4x + 1\) ứng với x và \(\Delta x\) là
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Lời giải:
Báo sai\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacqqHuo % arcaWG5bGaeyypa0JaamOzamaabmaabaGaeuiLdqKaamiEaiabgUca % RiaadIhaaiaawIcacaGLPaaacqGHsislcaWGMbWaaeWaaeaacaWG4b % aacaGLOaGaayzkaaaabaGaeyypa0ZaaeWaaeaacqqHuoarcaWG4bGa % ey4kaSIaamiEaaGaayjkaiaawMcaamaaCaaaleqabaGaaGOmaaaaki % abgkHiTiaaisdadaqadaqaaiabfs5aejaadIhacqGHRaWkcaWG4baa % caGLOaGaayzkaaGaey4kaSIaaGymaiabgkHiTmaabmaabaGaamiEam % aaCaaaleqabaGaaGOmaaaakiabgkHiTiaaisdacaWG4bGaey4kaSIa % aGymaaGaayjkaiaawMcaaaqaaiabg2da9iabfs5aejaadIhadaahaa % WcbeqaaiaaikdaaaGccqGHRaWkcaaIYaGaeuiLdqKaamiEaiaac6ca % caWG4bGaey4kaSIaamiEamaaCaaaleqabaGaaGOmaaaakiabgkHiTi % aaisdacqqHuoarcaWG4bGaeyOeI0IaaGinaiaadIhacqGHRaWkcaaI % XaGaeyOeI0IaamiEamaaCaaaleqabaGaaGOmaaaakiabgUcaRiaais % dacaWG4bGaeyOeI0IaaGymaiabg2da9iabfs5aejaadIhadaahaaWc % beqaaiaaikdaaaGccqGHRaWkcaaIYaGaeuiLdqKaamiEaiaac6caca % WG4bGaeyOeI0IaaGinaiabfs5aejaadIhaaeaacqGH9aqpcqqHuoar % caWG4bWaaeWaaeaacqqHuoarcaWG4bGaey4kaSIaaGOmaiaadIhacq % GHsislcaaI0aaacaGLOaGaayzkaaaaaaa!9404! \begin{array}{l} \Delta y = f\left( {\Delta x + x} \right) - f\left( x \right)\\ = {\left( {\Delta x + x} \right)^2} - 4\left( {\Delta x + x} \right) + 1 - \left( {{x^2} - 4x + 1} \right)\\ = \Delta {x^2} + 2\Delta x.x + {x^2} - 4\Delta x - 4x + 1 - {x^2} + 4x - 1 = \Delta {x^2} + 2\Delta x.x - 4\Delta x\\ = \Delta x\left( {\Delta x + 2x - 4} \right) \end{array}\)