Title: Review of Addition and Subtraction of fractions and Introduction to Simplifying Complex Fractions
1Review of Addition and Subtraction of fractions
and Introduction to Simplifying Complex
Fractions
2Review of Addition, Subtraction of Fractions
- To add or subtract rational expressions, a common
denominator is necessary... - Example Simplify
Find the LCD 6x
Now, rewrite the expression using the LCD of 6x
Simplify...
Add the fractions...
19 6x
3Lets try one with polynomials as denominators...
Find the LCD
(x 2)(x 2)
Rewrite the expression by multiplying the top and
bottom of each fraction by whatever is required
to get the LCD of (x 2)(x 2)
Simplify... (watch out for the negative!)
5x 22 (x 2)(x 2)
4Complex Fraction a fraction with a fraction in
the numerator and/or denominator.
- Such as
- How would you simplify this complex fraction?
- Multiply the top by the reciprocal of the bottom!
5Method 1For simplifying Complex Fractions
- Work on the numerator and denominator separately.
- Find the common denominator of the fractions on
the top and combine them. - Find the common denominator of the fractions on
the bottom and combine them. - Invert the bottom and multiply by the top.
- Simplify where possible.
6 Example
Invert the bottom and multiply
7Another Example
8Yet another example
9Method 2 For simplifying Complex Fractions
- To simplify complex fractions, find the LCD of
all the little fractions - Multiply every term by the LCD of all the little
fractions ... - Simplify
- Divide out where you can ...
10Using Method 2 To simplify complex fractions,
find the LCD of all of the little fractions
12x
Multiply every term by the LCD...
12x 1
12x 1
Simplify (divide out where you can )...
12x 1
12x 1
12
18
4
9
30 13
11Here is a complex fraction with polynomials using
method 2 ...
LCD of all of the little fractions
x(x 2)
Multiply every term by the LCD...
x(x 2) 1
Simplify (divide out where you can )...
x(x 2) 1
x(x 2)
x
6x2 12x
4x 8
x 6x2 16x 8
12The final example explores a problem that has a
fraction as one of its terms in a deep layer.
The method in question solves the equation from
the innermost fractions to the outer layer, by
finding the LCDs of that layer.
13Example Simplify
Step 1. Group and expand each fractional term.
Step 2. Find the LCD of the innermost fraction.
Step 3. Simplify.
Step 4. Add fractions
Step 5. Invert and multiply.
14Example (continued)
Step 6. Rewrite with LCD in both terms.
Step 7. Multiply and combine the fractions. At
the end , check to see if there are common
factors in the numerator and denominator that can
be used to reduce.
This is the final solution because there are no
common factors in the problem.