# Simplify multiple layers fractions

I have a complicated fraction

1/(4 TauTheta)+TauU/(gamma^2 (1+J)^2 TauDelta (1/TauEpsilon+1/(4 TauTheta)+(-1+J)/(4 TauTheta))^2 (TauDelta+TauU/(gamma^2 (1/TauEpsilon+1/(4 TauTheta)+(-1+J)/(4 TauTheta))^2)))-((1+J)^2 TauTheta+4 z1)/(4 (1+J)^2 TauTheta (TauTheta+z1))-TauU/(gamma^2 (1+J)^2 TauDelta (1/TauEpsilon+(-1+J)/(4 TauTheta)+1/(4 (TauTheta+z1)))^2 (TauDelta+TauU/(gamma^2 (1/TauEpsilon+(-1+J)/(4 TauTheta)+1/(4 (TauTheta+z1)))^2)))


Here is what it looks like. I want to simplify it into a factor with one layer, which means it looks like a/b. However, whenever I use Simplify or FullSimplify, it does not change. Could anyone help me? Thanks in advance!

Together seems to do the trick:

FullSimplify@Together@Test
(* (z1 (256 (-1 + J) (3 +
J) TauEpsilon^4 TauTheta^4 TauU^2 (TauTheta + z1)^2 +
16 gamma^2 TauEpsilon^2 TauTheta^2 TauU (2 TauTheta^2 (J
TauEpsilon + 4 TauTheta) ((-1 + J) J (3 + J) TauDelta TauEpsilon +
4 (-1 + J) (3 + J) TauDelta TauTheta -
4 TauEpsilon TauTheta) + 2 TauTheta ((-1 + J) J (3 + J) (-1 +
2 J) TauDelta TauEpsilon^2 + 2 (-1 + 4 J) (2 (-1 + J) (3 + J) TauDelta -
TauEpsilon) TauEpsilon TauTheta + 32 ((-1 + J) (3 + J) TauDelta - TauEpsilon) TauTheta^2) z1 + (4 TauEpsilon (TauEpsilon
- 2 J TauEpsilon - 8 TauTheta) TauTheta + (-1 + J) (3 +
J) TauDelta ((1 + 2 (-1 + J) J) TauEpsilon^2 +
8 (-1 + 2 J) TauEpsilon TauTheta + 32 TauTheta^2)) z1^2) +
gamma^4 (-1 + J) (3 + J) TauDelta^2 (J TauEpsilon +
4 TauTheta)^2 (-TauEpsilon z1 + J TauEpsilon (TauTheta + z1) +
4 TauTheta (TauTheta + z1))^2))/(4 (1 +
J)^2 TauTheta (gamma^2 TauDelta (J TauEpsilon + 4 TauTheta)^2 +
16 TauEpsilon^2 TauTheta^2 TauU) (TauTheta +
z1) (16 TauEpsilon^2 TauTheta^2 TauU (TauTheta + z1)^2 +
gamma^2 TauDelta (-TauEpsilon z1 + J TauEpsilon (TauTheta + z1) + 4 TauTheta (TauTheta + z1))^2)) *)


You can find this and many other function in the "Formula Manipulation" guide page.