When adding or subtracting rational expressions we will need a common denominator.
Simplify the resulting rational expression after adding or subtracting them.
Add or subtract.
If the rational expressions that we are adding or subtracting have unlike denominators then we will need to find the equivalent fractions with the same denominator. To do this multiply both the numerator and denominator of each expression by the factors needed to obtain a common denominator. To help determine the LCD, first factor the denominators.