Addition & Subtraction

Adding & Subtracting Rational Expressions

Fractions

Once the LCD is found, write equivalent fractions using the LCD as the denominator. Finally, add the fractions by adding the numerators and writing the sum over the LCD.

Example Add and simplify.

frac1

Step 1. Find the Least Common Denominator.

The LCD of 2 and 3 is 6.

Step 2. Rewrite the fractions with the LCD.

frac2

*Remember: frac3 and multiplying by 1 does not change the value of an expression.

Step 3. Add the fractions.

frac4

Step 4.Simplify the fraction, if necessary.