Warm-up: Here is an example to help you do this warm-up.
Warm-up:Here is an example to help you do this warm-
up.
Homework:
9.c add and subtract rational expressions
After this lesson you will be able to…Find the least common denominator for two
or more rational expressionsBuild up the fractions so that they all have
the LCDAdd or subtract the fractionsTo add or subtract fractions to simplify
complex fractions
BIG IDEA!!!You can only add/subtract fractions
with the same denominator!
Procedure:If the fractions have the same
denominator…1. Add/Subtract the numerators.
WATCH OUT! Minus signs distribute!
1. Keep the same denominator.2. Reduce answer if possible.
Example 1:3 4 2
30 30m n m n
n n
Example 2:
2 2
2 5 310 10
y x yx y x y
If the fractions don’t have the same denominators…You MUST make them have the same
denominator before you can add or subtract them.
Building a Least Common Denominator (LCD)BIG IDEA!!!
An LCD will show the factors of both denominators!
PROCEDURE:1. Factor each denominator completely.2. Multiply the top and bottom of each
fraction by whatever factors are missing from that denom.
3. Rewrite as one large fraction. This will help you avoid sign errors.
4. Multiply out the numerator and then combine like terms.
5. Factor and reduce if possible.
Example 3:
Example 4:
Example 5:
Example 6:
Example 7:
2 2
5 24 5 14
x xx x x
Simplifying Complex FractionsExample 8:
Example 9:
Homework:HW ST 9.c both sides