Cho hàm số $% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY-Hhbbf9v8qqaqFr0xc9pk0xbb % a9q8WqFfeaY-biLkVcLq-JHqpepeea0-as0Fb9pgeaYRXxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape % GaamOzamaabmaapaqaa8qacaWG4baacaGLOaGaayzkaaGaeyypa0Za % aiqaa8aaeaqabeaapeGaamiEaiaaykW7caaMc8UaaGPaVlaabUgaca % qGObGaaeyAa8aacaaMe8+dbiaadIhacqGHLjYScaaIXaaapaqaa8qa % caaIXaGaaGPaVlaaykW7caaMc8UaaGPaVlaabUgacaqGObGaaeyAa8 % aacaaMe8+dbiaadIhacqGH8aapcaaIXaaaaiaawUhaaaaa!579F! f\left( x \right) = \left\{ \begin{array}{l} x\,\,\,{\rm{khi}}\;x \ge 1\\ 1\,\,\,\,{\rm{khi}}\;x < 1 \end{array} \right.$, tính tích phân $% MathType!MTEF!2!1!+- % feaahqart1ev3aqaMnevLHfij5gC1rhimfMBNvxyNvgaCLMB0XfBP1 % wA0n3x7btFETNm9TNzCXwzMrhkGGhiCjxANHgDPWfDLHhD7rwF41ha % tCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBae % XatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVCI8 % FfYJH8YrFfeuY-Hhbbf9v8qqaqFr0xc9pk0xbba9q8WqFfeaY-biLk % VcLq-JHqpepeea0-as0Fb9pgeaYRXxe9vr0-vr0-vqpWqaaeaabiGa % ciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaapeWaa8qCa8aabaWdbi % aadAgadaqadaWdaeaapeGaamiEaaGaayjkaiaawMcaaiaabsgacaWG % 4baal8aabaWdbiaaicdaa8aabaWdbiaaikdaa0Gaey4kIipaaaa!5968! \int\limits_0^2 {f\left( x \right){\rm{d}}x}$.

$% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY-Hhbbf9v8qqaqFr0xc9pk0xbb % a9q8WqFfeaY-biLkVcLq-JHqpepeea0-as0Fb9pgeaYRXxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape % Waa8qCa8aabaWdbiaadAgadaqadaWdaeaapeGaamiEaaGaayjkaiaa % wMcaaiaabsgacaWG4baal8aabaWdbiaaicdaa8aabaWdbiaaikdaa0 % Gaey4kIipakiabg2da9maapehapaqaa8qacaWGMbWaaeWaa8aabaWd % biaadIhaaiaawIcacaGLPaaacaqGKbGaamiEaaWcpaqaa8qacaaIWa % aapaqaa8qacaaIXaaaniabgUIiYdGccqGHRaWkdaWdXbWdaeaapeGa % amOzamaabmaapaqaa8qacaWG4baacaGLOaGaayzkaaGaaeizaiaadI % haaSWdaeaapeGaaGymaaWdaeaapeGaaGOmaaqdcqGHRiI8aaaa!5515! \int\limits_0^2 {f\left( x \right){\rm{d}}x} = \int\limits_0^1 {f\left( x \right){\rm{d}}x} + \int\limits_1^2 {f\left( x \right){\rm{d}}x}$$% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY-Hhbbf9v8qqaqFr0xc9pk0xbb % a9q8WqFfeaY-biLkVcLq-JHqpepeea0-as0Fb9pgeaYRXxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape % Gaeyypa0Zaa8qCa8aabaWdbiaabgdacaqGKbGaamiEaaWcpaqaa8qa % caaIWaaapaqaa8qacaaIXaaaniabgUIiYdGccqGHRaWkdaWdXbWdae % aapeGaamiEaiaabsgacaWG4baal8aabaWdbiaaigdaa8aabaWdbiaa % ikdaa0Gaey4kIipaaaa!45EC! = \int\limits_0^1 {{\rm{1d}}x} + \int\limits_1^2 {x{\rm{d}}x}$$% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY-Hhbbf9v8qqaqFr0xc9pk0xbb % a9q8WqFfeaY-biLkVcLq-JHqpepeea0-as0Fb9pgeaYRXxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape % Gaeyypa0ZaaqGaa8aabaWdbiaadIhaaiaawIa7a8aadaqhaaWcbaWd % biaaicdaa8aabaWdbiaaigdaaaGccqGHRaWkdaabcaWdaeaapeWaaS % aaa8aabaWdbiaadIhapaWaaWbaaSqabeaapeGaaGOmaaaaaOWdaeaa % peGaaGOmaaaaaiaawIa7a8aadaqhaaWcbaWdbiaaigdaa8aabaWdbi % aaikdaaaGccqGH9aqpdaWcaaWdaeaapeGaaGynaaWdaeaapeGaaGOm % aaaaaaa!4616! = \left. x \right|_0^1 + \left. {\frac{{{x^2}}}{2}} \right|_1^2 = \frac{5}{2}$