Line 3: Line 3:
 
<math>x(t)=e^{-2jt} \to sys \to y(t)=te^{2jt}</math>
 
<math>x(t)=e^{-2jt} \to sys \to y(t)=te^{2jt}</math>
  
We want to know the output associated with the input <math>x(t)=cos(2t)</math>. If you expand <math>cos(2t)</math> into two exponentials you will get <math>\frac{e^{2jt} + e^{-2jt}}{2}</math>. Now you can use linearity to solve the problem. Linearity implies that if <math>x(t)=cos(2t)</math> then <math>y(t)=tcos(-2t)=tcos(2t)</math>.
+
We want to know the output associated with the input <math>x(t)=cos(2t)</math>. If you expand <math>cos(2t)</math> into two exponentials you will get <math>\frac{e^{2jt} + e^{-2jt}}{2}</math>. Now you can use linearity to solve the problem.
 +
 
 +
<math>\frac{1}{2}e^{2jt} + \frac{1}{2}e^{-2jt} \to sys \to tcos(2t)</math>

Latest revision as of 12:27, 18 September 2008

$ x(t)=e^{2jt} \to sys \to y(t)=te^{-2jt} $

$ x(t)=e^{-2jt} \to sys \to y(t)=te^{2jt} $

We want to know the output associated with the input $ x(t)=cos(2t) $. If you expand $ cos(2t) $ into two exponentials you will get $ \frac{e^{2jt} + e^{-2jt}}{2} $. Now you can use linearity to solve the problem.

$ \frac{1}{2}e^{2jt} + \frac{1}{2}e^{-2jt} \to sys \to tcos(2t) $

Alumni Liaison

Basic linear algebra uncovers and clarifies very important geometry and algebra.

Dr. Paul Garrett