Mathematics » Rational Expressions and Equations » Add and Subtract Rational Expressions with Unlike Denominators

Add and Subtract Rational Expressions Summary II

Key Concepts

  • Find the Least Common Denominator of Rational Expressions
    1. Factor each expression completely.
    2. List the factors of each expression. Match factors vertically when possible.
    3. Bring down the columns.
    4. Multiply the factors.
  • Add or Subtract Rational Expressions
    1. Determine if the expressions have a common denominator.
      Yes – go to step 2.
      No – Rewrite each rational expression with the LCD.
      • Find the LCD.
      • Rewrite each rational expression as an equivalent rational expression with the LCD.
    2. Add or subtract the rational expressions.
    3. Simplify, if possible.

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