4.8 Exercises 85 Exercise 4.5 a) t h r shift, theorcm (3.22) b) t l i ~modultxtion theorem ( i.23) by sihstitutiiig (4.1) = 1’ - r arid T = s‘ - a Exercise 4.7 Prow eqitatioii (4.24)( t h e aiid frccpicncy scdirrg) by substituting t = at’ into (it.1) xereise 4.8 Uerivcx t h r trarisforni pairs irr Tal~lr 4.1 starting with t h r transform pair I X ( )= It$>{s } > (I irsiiig the Ilieormnr from Scction 4.7 - .i,