Rational Expressions 6 - Subtracting with Common Denominator

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Taught by YourMathGal
  • Currently 4.0/5 Stars.
5847 views | 2 ratings
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Meets NCTM Standards:
Lesson Summary:

In this lesson on subtracting rational expressions with a common denominator, we learn to use the distributive property and simplify the numerator by factoring, canceling only when possible. While we subtract numerators and write the difference over the common denominator, we must remember not to leave a 1 in the denominator. The lesson also explores canceling when there are opposite expressions in the numerator and the importance of factoring.

Lesson Description:

How to subtract rational expressions that already have a common denominator, and how to simplify if it is possible to cancel.

More free YouTube videos by Julie Harland are organized at http://yourmathgal.com

Questions answered by this video:
  • How do you subtract and simplify 4x/(x - 1) - 4/(x - 1)?
  • How do you subtract and simplify rational expressions that have a common denominator?
  • How do you subtract rational expressions if a numerator has more than one term?
  • How can you subtract and simplify (5x - 8)/(2x + 3) - (2x + 6)/(2x + 3)?
  • Why does -(2x + 6) equal -2x - 6?
  • How do you subtract, factor, and simplify (x^2 + 9x)/(x + 7) - (4x + 14)/(x + 7)?
  • What does (3x + 4)/(2x^2 + 5x - 3) - (5x + 3)/(2x^2 + 5x - 3) equal?
  • How do you know if you can simplify (-2x + 1)/((2x - 1)(x + 3))?
  • Staff Review

    • Currently 4.0/5 Stars.
    This video is very similar to the last video on adding rational expressions with common denominators. This time, however, we are subtracting. This is similar, but you must be careful to distribute the - sign to all terms being subtracted. This has some great example problems explained very well.