Solving a Red Equation: Where Did I Go Wrong?

[asi123]

Homework Statement

Hey guys.
I have this equation in red (in the pic) which I need to solve

http://img241.imageshack.us/img241/9323/scan0004n.jpg

As you can see I came up with with 2*t0.
When I solve it in Matematica I come up with t2=t0 without the 2.
Also, their answer in the book is also only t0.
Can someone please tell me where is my mistake please?

Thanks.

Homework Equations

The Attempt at a Solution

 

[Hootenanny]

Everything looks good until the final line. Why have you suddenly changed from T = t₂ to T = 2t₀? What is t₀? How does it relate to t₂?