Important: Typo in equation (14) in project 1

A typo which can, and perhaps already has caused much frustration has been brought to my attention: In the expression for Omega_m in equation (14) there is a term (x_2)^3. This is a mistake, the x_2 should be squared like the other terms, not cubed. So, (x_2)^2, not ^3.

I am very sorry for this. My apologies to everyone who has had to struggle to try to derive a wrong result.