I think the problem is here free(polynomialArrayindex. PolynomialTerm) if index > num_polynomial, then the value here polynomialArrayindex. PolynomialTerm is garbage.
You don't need to free it. Instead you should write it something like that.
I think the issue is that subtract is returning a pointer into your dynamically allocated array, but then insert realloc's that array, leaving the pointer returned by subtract (passed into insert as element) dangling.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.