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082-Engineering-Mathematics-Anthony-Croft-Robert-Davison-Martin-Hargreaves-James-Flint-Edisi-5-2017

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18 Taylorpolynomials,

Taylorseriesand

Maclaurinseries

Contents 18.1 Introduction 507

18.2 Linearizationusingfirst-orderTaylorpolynomials 508

18.3 Second-orderTaylorpolynomials 513

18.4 Taylorpolynomialsofthenthorder 517

18.5 Taylor’sformulaandtheremainderterm 521

18.6 TaylorandMaclaurinseries 524

Reviewexercises18 532

18.1 INTRODUCTION

Often the value of a function and the values of its derivatives are known at a particular

pointandfromthisinformationitisdesiredtoobtainvaluesofthefunctionaroundthat

point.TheTaylorpolynomialsandTaylorseriesallowengineerstomakesuchestimates.

Oneapplicationofthisisinobtaininglinearizedmodelsofnon-linearsystems.Thegreat

advantageofalinearmodelisthatitismucheasiertoanalysethananon-linearone.Itis

possibletomakeuseoftheprincipleofsuperposition:thisallowstheeffectsofmultiple

inputstoasystemtobeconsideredseparately,andtheresultantoutputtobeobtainedby

summing the individual outputs.

Oftenasystemmaycontainonlyafewcomponentsthatarenon-linear.Bylinearizing

theseitisthenpossibletoproducealinearmodelforthesystem.Wesawanexampleof

thiswhenweanalysedafluidsysteminEngineeringapplication10.6.Althoughelectricalsystemsareoftenlinear,mechanical,thermalandfluidsystems,orsystemscontainingamixtureofthese,arelikelytocontainsomenon-linearcomponents.Unfortunately

itmaynotbepossibletoobtainasufficientlyaccuratelinearmodelforeverynon-linear

systemas weshall see inthischapter.

Taylorpolynomialsofhigherdegreecanbefoundwhichapproximatetoagivenfunction.ThisisdealtwithinSections18.3and18.4.Thedifferencebetweenagivenfunction

andthecorrespondingTaylorpolynomialiscoveredinSection18.5.Thechaptercloses

with a treatment of Taylor and Maclaurin series.

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