This must be buddy no. 468 to explain to me the factorization of a trinomial ... At least, it would be helpful if they spoke a comprehensible Inklish! 😂😂
Your step one is unnecessary, bc you can just find the factors of both 6x² and -10 right away, so idk why you did that, I guess it's to showcase the method. but still...
The first functional equation yields f(x) = -3x -1/3 as the only answer, and the second, f(x) = 4/3x. That's easy to see in both by substituting x by -x (should still work fine) and manipulating the resulting system to find f(x) isolated. That means the given functional system is actually impossible...