subtract with unlike denominators

• When subtracting fractions, we need a common denominator
• Steps to subtract fractions with unlike denominators

  1. Find the least common multiple between the denominators

  2. Rename the fractions with the common denominator

  3. Subtract the numerators

  4. Simplify the result if possible
• The least common multiple is used as the common denominator because smaller numbers are generally easier to work with
• Least common multiple


  The smallest positive integer that is divisible by both denominators
• Renaming fractions with a common denominator

  1. Multiply the numerator and denominator by the same number to get the new denominator

  2. Whatever is done to the denominator must also be done to the numerator to keep the fraction equivalent
• When subtracting fractions with a common denominator

  Subtract the numerators and keep the common denominator
• Simplifying fractions involves finding the greatest common factor between the numerator and denominator and dividing both by that factor