Question

4-x^2/x^2+7X+12/2x-4/x+3

Answer 1

you want to add some parentheses, or at least some spaces, so we can work with that? As written, using the normal order of operations, you have

4-x^2/x^2+7x+12/2x-4/x+3
4-1+7x+6/x-4/x+3
3+7x+2/x+3
6 + 7x + 2/x

I doubt that is what you had in mind.