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

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21 TheLaplacetransform

Contents 21.1 Introduction 627

21.2 DefinitionoftheLaplacetransform 628

21.3 Laplacetransformsofsomecommonfunctions 629

21.4 PropertiesoftheLaplacetransform 631

21.5 Laplacetransformofderivativesandintegrals 635

21.6 InverseLaplacetransforms 638

21.7 UsingpartialfractionstofindtheinverseLaplacetransform 641

21.8 FindingtheinverseLaplacetransformusingcomplexnumbers 643

21.9 Theconvolutiontheorem 647

21.10 Solvinglinearconstantcoefficientdifferentialequationsusing

theLaplacetransform 649

21.11 Transferfunctions 659

21.12 Poles,zerosandthesplane 668

21.13 Laplacetransformsofsomespecialfunctions 675

Reviewexercises21 678

21.1 INTRODUCTION

TheLaplacetransformisusedtosolvelinearconstantcoefficientdifferentialequations.

This is achieved by transforming them to algebraic equations. The algebraic equations

are solved, then the inverse Laplace transform is used to obtain a solution in terms of

the original variables. This technique can be applied to both single and simultaneous

differentialequationsandsoisextremelyusefulgiventhatdifferentialequationmodels

arecommon as we sawinChapters 19 and 20.

TheLaplacetransformisalsousedtoproducetransferfunctionsfortheelementsofan

engineeringsystem.Thesearerepresentedindiagrammaticformasblocks.Thevarious

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