so 1/(x2-1) is equivalent to 1/(x+1)(x-1) you notice that there is a common part of (x+1) in both fraction denominators. in order to add fractions, the denominators must be the same, so multiply 1/(x+1) by (x-1)/(x-1), which doesnt change anything since it is essentially one, you now have two fractions with the same denominator. just add the numerators. you can do the same for the other fraction questions.