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/(x1) = ? thanks for you help Hi Donna,Adding and subtracting rational exprressions is very similar to adding and subtracting fractions. Suppose you have 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 Penny
