Example #3 a(t)= 3eu(t)-2e u(t) X( 3e2t-2e-te-stdt 0 3/c-(s-2)tat-2 0e-(s+1)tt BOTH required Requires es>2 Requires es>-1 ROC intersection 小 +7 +7 X 8-2)(s+1)s2-8 9e{s}>2 gn Notation S-plane o—zerO g Q: Does x(t have FT?Example #3 Notation: × — pole ° — zero Q: Does x ( t) have FT? BOTH required → ROC intersection