# Math Help - Addition/ subtraction of fractions

1. ## Addition/ subtraction of fractions

Hi. I am trying to re-teach myself maths having not done any for years.

on the above subject I am having trouble when squared terms are introduced in the denominator.

examples:

1/x2-1. + 1/x+1

2/a2-1. + 3/a-1

1/x2+2x+1. + 1/x+1

any help is greatly appreciated

alan

2. ## Re: Addition/ subtraction of fractions

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.