I did some digging about FullSimplify but did not find something concrete about my problems and I think they are too elementary to pass.
1)This example is not problematic but I will use it as the prototype.
-((2 k^2)/3) + 8 k^4 M^2 - 12 k^2 M^2 \[Omega]^2 // FullSimplify.
2/3 k^2 (-1 + 6 M^2 (2 k^2 - 3 \[Omega]^2))
which is just fine and what I actually need. Notice that M^2 gets factored.
2)Now a slightly modified version of 1)
-2 k^2 + 12 k^4 M^2 - 18 k^2 M^2 \[Omega]^2 // FullSimplify
2 k^2 (-1 + 6 k^2 M^2 - 9 M^2 \[Omega]^2)
Now this is problematic, notice that M^2 did not get factored in this case as in Output1 and therefore the expression is not fully simplified.
3)A simpler problematic example.
(2 k^2)/3 - 4 k^4 // FullSimplify
(2 k^2)/3 - 4 k^4 M^2
In this case no simplification was performed whatsoever, even if you try Simplify Output3 is again the same. For the sake of clarity by simplification I mean that the output should have k^2 factored from both terms.
1)Does anyone have any idea why is this happening in Output2 in contrast to Output1?
2)What about Output3? Isn't it too trivial for FullSimplify to fail?
3)Any possible fixes?