>>18
It won't factor like that because you can't cancel terms in that manner, example (a + b)/(a + c) does not equal b/c. You have to do some factoring work on the top and on the bottom, then look for matching factors top and bottom that you can then cancel. The top: x^4 - x has a common factor, so rewrite it, then you will see that one of the factors is a difference of cubes which has a way of factoring like this: a^3 – b^3 = (a – b)(a^2 + ab + b^2). The bottom: you have a difference of squares which has a way of factoring like this: a^2 - b^2 = (a - b)(a + b). Now because the first square is actually a power of degree 4, one of the factors will be another difference of squares of degree 2 that you can further factor.
>>19
You are probably meant to compress the expressing into a single fraction form. First factor all the fraction bottoms. (Notice that the second fraction has a difference of squares.) You will then need to make the fractions have a common denominator so that they all have the same factors on the bottom, allowing you to compress the expression into a single fraction. It is like when you have 1/6 + 1/8 and you have to multiply 1/6 by 4/4 and multiply 1/8 by 3/3 so that both fractions will have 24 on the bottom. But for you, you have to multiply top and bottom of each fraction by a binomial factor. Then you simplify the top of the fraction.