# Adding and subtracting rational expressions

4 videos
5 skills
Learn how to add and subtract rational expressions. Like multiplication and division, this skill has a remarkable affinity to adding and subtracting fractions!

### Add and subtract rational expressions with the same denominator

PRACTICE PROBLEMS
Ease into the realm of rational-expression-addition-and-subtraction by first working with expressions that have the same denominator.

### How to add two rational expressions with different denominators (example)

VIDEO 2:44 minutes
Sal rewrites a/b+c/d as a single rational expression.

### Add and subtract rational expressions with relatively prime denominators

PRACTICE PROBLEMS
Add and subtract rational expressions with relatively prime denominators by manipulating them to have the same denominators.

### How to find the least common multiple of two numbers (example)

VIDEO 4:16 minutes
Sal finds the lcm (least common multiple) of 12 and 36, and of 12 and 18. He shows how to do that using the prime factorization method, which is a just great!

### How to find the least common multiple of two numbers with repeating factors (example)

VIDEO 2:35 minutes
Sal finds the lcm (least common multiple) of 25 and 30.

### Least common multiple

PRACTICE PROBLEMS
Find the lcm (least common multiple) of pairs of integers.

### Add and subtract rational expressions with factored denominators

PRACTICE PROBLEMS
Add and subtract rational expressions with factored denominators by manipulating them to have the same denominators.

### How to subtract rational expressions by finding the least common multiple (example)

VIDEO 4:36 minutes
Sal performs the following subtraction and simplifies the result: (a-2)/(a+2) - (a-3)/(a^2+4a+4).

### Add and subtract rational expressions by finding the least common multiple

PRACTICE PROBLEMS
Master the skill of rational-expression-addition-and-subtraction by working with expressions whose denominators aren't factored and may or may not have shared factors.