How can i turn a factor like this x(x+1) + x(1-x) into the same things in order to factor? If that wasnt clear, how can I turn a polynomial with - into a polynomial with + so I can do the last step and factor
Generally speaking, you can't turn an x - 1 into an x + 1.
You can turn a 1 - x into an x - 1 by factoring out a negative one: 1 - x = -1(x - 1)