TEXT: Intermediate Algebra by Miller, O’Neill & Hyde
Videos from Khan Academy.
Day 18 – Addition & Subtraction of Rational Expressions
We can easily add or subtract 2 rational expressions that have the same denominator using one of the following:
If the denominators are not the same, then find the Least Common Multiple (LCM) of the Denominators, better known as the Least Common Denominator (LCD):
Once the LCD is found then you must multiply the numerator and denominator of a particular fraction by whatever factors are needed to get the denominator to be the common one. Once the denominators are the same, then proceed as before:
An example subtracting 2 rational expressions with monomial denominators:
One example with more general denominators: