Adding and subtracting Rational expressions. I am in grade 10 and I am a student here is an example of the questions:

1/(x+1) - 1/(x-1) = ?

thanks for you help

Hi Donna,

Adding and subtracting rational exprressions is very similar to adding and subtracting fractions. Suppose you have

You first need to find a common denominator. For denominators of 3 and 5 a common denominator is 3 x 5 = 15. Thus for one-third multiply the numerator and denominator by 5 and for one-fifth multiply the numerator and denominator by 3. That is:

Likewise for denominators of x + 1 and x - 1 a common denominator is (x + 1) times (x - 1). Thus multiply the numerator and denominator of the first fraction by (x - 1) and multiply the numerator and denominator of the second fraction by (x + 1). You the get

I hope this helps,
Penny
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