Cho hàm số f(x) xác định trên R bởi \(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOzamaabm % aabaGaamiEaaGaayjkaiaawMcaaiabg2da9maakeaabaGaamiEaaWc % baGaaG4maaaaaaa!3C40! f\left( x \right) = \sqrt[3]{x}\). Giá trị f’(-8) bằng:
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Lời giải:
Báo sai\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEaiabg2 % da9maakeaabaGaamiEaaWcbaGaaG4maaaaiiaakiab-jDiElaadMha % daahaaWcbeqaaabaaaaaaaaapeGaaG4maaaakiabg2da9iaadIhacq % WFshI3caaIZaGaamyEa8aadaahaaWcbeqaa8qacaaIYaaaaOGaaiOl % aiqadMhagaqbaiabg2da9iaaigdacqWFshI3ceWG5bGbauaacqGH9a % qpdaWcaaqaaiaaigdaaeaacaaIZaGaamyEa8aadaahaaWcbeqaa8qa % caaIYaaaaaaakiabg2da9maalaaabaGaaGymaaqaaiaaiodadaqada % qaa8aadaGcbaqaaiaadIhaaSqaaiaaiodaaaaak8qacaGLOaGaayzk % aaWdamaaCaaaleqabaWdbiaaikdaaaaaaaaa!5807! y = \sqrt[3]{x} \Rightarrow {y^3} = x \Rightarrow 3{y^2}.y' = 1 \Rightarrow y' = \frac{1}{{3{y^2}}} = \frac{1}{{3{{\left( {\sqrt[3]{x}} \right)}^2}}}\)
\(% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaaccaGae8N0H4 % TabmyEayaafaWaaeWaaeaacqGHsislcaaI4aaacaGLOaGaayzkaaGa % eyypa0ZaaSaaaeaacaaIXaaabaGaaGymaiaaikdaaaaaaa!3FDE! \Rightarrow y'\left( { - 8} \right) = \frac{1}{{12}}\)