# Rewriting Particular soltution

#### polarbear123

##### New member
Hello,
I have found a particular solution int he form of
y=Pcos(ax)+Qsin(ax)
but have to find a particular in the form of
y=Re(Aeix)
How can I rewrite, or change the equation so the first is the latter?

#### HallsofIvy

##### Elite Member
$$\displaystyle cos(ax)= \frac{e^{iax}+ e^{-iax}}{2}$$
$$\displaystyle sin(ax)= \frac{e^{iax}- e^{-iax}}{2i}$$