How to convert between function forms of single frequency signals
Easier yet.

$$
\begin{aligned}
 ( 3 + 4j ) e^{j\rho} + ( 3 - 4j ) e^{-j\rho} 
&amp;= 3 ( e^{j\rho} + e^{-j\rho} ) + 4j( e^{j\rho} - e^{-j\rho} ) \\
&amp;= 3(2 \cos(\rho)) + 4j( 2j\sin(\rho)) \\
&amp;= 6 \cos(\rho) - 8 \sin(\rho)
\end{aligned}
$$