Starting with the equation below, I need to:
- Show that there is a range of values for a for which Ωm≈1
- Derive expressions for the values of a at the endpoints of this range.
Ωm(a) = Ωm0/[Ωm0+Ωr0/a+Ωv0a3].
(0 signifies present day values, m=matter, r=radiation, v=vacuum)
The Attempt at a Solution
Just setting Ωm=1 leads to a4 = -Ωr0/Ωv0, which gives imaginary values for a, which is obviously not right. However, I can't see any other way of solving this problem to get real values...
Thanks in advance,