in solving wave equation by Fourier transform after taking fourier transform of wave equation $\frac{\partial^2y}{\partial^2x}=\frac{1}{v^2} \frac{\partial^2y}{\partial t^2}$ we get $(-ia)^2 Y(a,t)=\frac{1}{v^2}\frac{d^2Y(a,t)}{dx^2}$ this is ok. now how we can get to this: $Y(a,t)=F(a)e^{(+-)ivat}$
tanks.