A light-signal, which is proceeding along the positive axis of x, is transmitted according to the equation
x = ct or
Since the same light-signal has to be transmitted relative to k' with the velocity c, the propagation relative to the system k' will be represented by the analogous formula
x'-cl'=0
By adding (or subtracting) equations (3) and (4), and introducing for convenience the constants a and b in place of the constants
and
where
A light-signal, which is proceeding along the positive axis of x, is transmitted according to the equation
x = ct or
Since the same light-signal has to be transmitted relative to k' with the velocity c, the propagation relative to the system k' will be represented by the analogous formula
x'-cl'=0
By adding (or subtracting) equations (3) and (4), and introducing for convenience the constants a and b in place of the constants
and
where