Possible Duplicate:
How would I rearrange this equation to make the subject $t$?
The scenario is as follows:
A sub-atomic particle is travelling in a straight line through a tubular cloud-chamber that is 28 cm long. The particle is subjected to an electromagnetic field that reverses the direction of the particle so that it disappears from the cloud-chamber. Almost instantaneously with the disappearance of the first particle, a second particle enters the chamber from the other direction. This particle is subjected to the same electromagnetic field so that its direction is also reversed and it disappears from the cloud-chamber after a period of time along the same trajectory as the first particle would have done if the electromagnetic field had not been applied. It is possible to model approximately these events with the function
$s(t) = 4t + \frac2{t-3} + \frac23$
where s represents the position of either particle in the tubular cloud-chamber measured in centimetres, while t represents the time in nano-seconds.
The question is:
When does the first particle actually leave the cloud-chamber according to the model?
[Hint: consider s(t) = 0]