492 Appendix A Solutions t-othe Exercises Yh(t) = + + l5(.jw) = + I - - += E ,.' -/ 1- - To produce the desired clrange of sign (+ - -+) the sigri of the argument t-~crcvcrscd (+- +- ) a.; ell forming the complex coirjugatc (++ ): Y(,(pd)= X * ( - , / w ) iiitist yJt) = + - Both imaginary parts chnngc sign: - (JW) =X + * (j.11 .*