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1、Chapter1Answers1.6(a).NoBecausewhent<0,=0.(b).NoBecauseonlyifn=0,hasvaluable.(c).YesBecauseN=4.1.9(a).T=/5Because=10,T=2/10=/5.(b).Notperiodic.Because,whileisnotperiodic,isnotperiodic.(c).N=2Because=7,N=(2/)*m,andm=7.(d).N=10Because,thatis=3/5,N=(2/)*m,andm=3.(e).Notperiodic.Because=3/5,N=(2/)*m=1
2、0m/3,it’snotarationalnumber.1.14A1=3,t1=0,A2=-3,t2=1or-1Solution:x(t)isisBecause,=3g(t)-3g(t-1)or=3g(t)-3g(t+1)1.15.(a).y[n]=2x[n-2]+5x[n-3]+2x[n-4]Solution:Then,(b).No.Forit’slinearity.therelationshipbetweenandisthesamein-outrelationshipwith(a).youcanhaveatry.1.16.(a).No.Forexample,whenn=0,y[0]=x
3、[0]x[-2].Sothesystemismemory.(b).y[n]=0.Whentheinputis,then,,soy[n]=0.(c).No.Forexample,whenx[n]=0,y[n]=0;whenx[n]=,y[n]=0.Sothesystemisnotinvertible.1.17.(a).No.Forexample,.Soit’snotcausal.(b).Yes.Because:,1.21.Solution:Wehaveknown:(a).(b).(c).(d).1.22.Solution:Wehaveknown:(a).(b).(e).(g)1.23.Sol
4、ution:Forthen,(a).(b).(c).1.24.Solution:For:then,(a).(b).(c).1.25.(a).Periodic.T=/2.Solution:T=2/4=/2.(b).Periodic.T=2.Solution:T=2/=2.(d).Periodic.T=0.5.Solution:So,T=2/4=0.51.26.(a).Periodic.N=7Solution:N==7,m=3.(b).Aperriodic.Solution:N=,it’snotrationalnumber.(e).Periodic.N=16Solutionasfollow:i
5、nthisequation,,it’speriodisN=2*m/(/4)=8,m=1.,it’speriodisN=2*m/(/8)=16,m=1.,it’speriodisN=2*m/(/2)=4,m=1.So,thefundamentalperiodofisN=(8,16,4)=16.1.31.SolutionBecause.AccordingtoLTIproperty,Extraproblems:1.SupposeSketch.Solution:2.SupposeSketch:(1).(2).Solution:(1).(2).Chapter22.1Solution:Becausex
6、[n]=(120–1),h[n]=(202),then(a).So,(b).accordingtothepropertyofconvolutioin:(c).2.3Solution:thefigureofthey[n]is:2.5Solution:Wehaveknown:,,()Then,,So,y[4]=5,thenAndy[14]=0,then2.7Solution:（a）,(b),(c)SisnotLTIsystem..(d),2.8Solution:Then,Thatis,2.10Solution:(a).Weknow:Then,thatis,So,(b).Fromthefigur
7、eof,onlyif,wouldcontainmerelytherediscontinuities.2.11Solution:(a).(b).(c).It’sobviousthat.2.12SolutionConsideringfor,wecanobtain.(Becausemustbenegetive,for).2.19Solution:(a).Wehaveknown:(1)(2)from(1),from(2),the
