Find the next three terms 486,162,54

For this case we have the following equation:

We must clear the value of the variable "x" as a function of r, s and t:

If we multiply by "r" on both sides of the equation we have:

If we subtract "t" on both sides of the equation we have:

If we divide by "2" on both sides of the equation we have:

Thus, the value of the variable "x" is: