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1、Threesolutionstocommonproblemsinprimaryschoolmathematics（小学数学常用的三种解题思路）Threesolutionstocommonproblemsinprimaryschoolmathematics"Directthinking"istheconventionalthinkinginsolvingproblems.Itisusuallythroughanalysis,synthesis,inductionandothermethodstofi
2、ndthewaytosolveproblemsdirectly.[]forwardcomprehensiveideasstartingfromtheknownconditions,selectthenumberoftwoknownaccordingtotherelationshipbetweenthenumberofproposedcansolvetheproblem;thentheamountcalculatedbytheconditionknownasnew,collocationandoth
3、erknownconditions,andthenputforwardtheproblemcanbesolved;thisstepbystepiscalculateduntilrequiredthesolutionssofar.Thisisthedirectionofthecomprehensiveapproach,theuseofthisapproachtosolvetheproblemcalledcomprehensivemethod".1brothersridegoouting,brothe
4、rofthefirst,aspeedof200metersperminute,5minutesafterstartinghisbrother,brotherwithadog,withaspeedof250metersperminuteaftertheyoungerbrother,andthedogwithaspeedof300metersperminutetobrotherchase,returnimmediatelyafterbrother,see.Brotherandbrotherimmedi
5、atelytochase,catchupuntilthebrotheryoungerbrother,thenthedogranmanykilometers?Analysis(followthegeneraldirectionofthinking):(1)accordingtotheyoungerbrother'sspeedfor200metersperminute,starting5minutesoftheconditions,whatcanIaskfor?Canfindouthowmanymet
6、erstheyoungerbrotherwalked,thatis,thedistancethattheelderbrotherfollowstheyoungerbrother.(2)accordingtomybrother,thespeedis200metersperminute,andthespeedofmybrotheris250metersperminute.WhatcanIaskfor?Youcanfigureouthowmanymetersabrothercancatchhisbrot
7、hereveryminute.(3)aftercalculating,wecanknowthatthedistanceofbrothercatchinghisyoungerbrotheris1000meters,andthedistancethathecancatcheveryminuteis50meters.Whatcanweaskforunderthesetwoconditions?Youcanfigureoutthetimeyourbrotherwillneedtocatchupwithhi
8、sbrother.(4)thedogisrunningbackandforthbetweenhisbrotherandhisbrother.Itlooksverycomplicated.Whenyouthinkaboutit,whattimedoesthedogrunwiththesametime?Thetimethedogrunsisthesameasthatofhisbrother'sbrother.(5)adogisknowntorunbetweenhisbrotherand
