Post on 17-Jan-2016
Chapter 9Chapter 9
Section 5Section 5
Adding and Subtracting Adding and Subtracting Rational ExpressionsRational Expressions
Review ProblemsReview Problems
Find the least common multiple of Find the least common multiple of the two numbers. the two numbers. 7, 217, 21 24, 1024, 10
11,1711,17
Add or SubtractAdd or Subtract
38
7
19
5 25
3
15
2
Add or SubtractAdd or Subtract
36
5
24
7 45
7
12
11
How to find the LCM/LCDHow to find the LCM/LCD(Least Common Multiple/Denominator)(Least Common Multiple/Denominator)
1.1. Factor the denominator into its Factor the denominator into its prime factors (as small as each will prime factors (as small as each will go).go).
2.2. Write each prime factor the Write each prime factor the greatest number of times it appears greatest number of times it appears in either expression.in either expression.
3.3. Simplify where possible.Simplify where possible.
Find the Least Common Find the Least Common MultipleMultiple
4x4x2 2 – 36 and 6x– 36 and 6x22 + 36x +54 + 36x +54
Find the Least Common Find the Least Common MultipleMultiple
3x3x2 2 – 9x – 30 and 6x + 30– 9x – 30 and 6x + 30
Find the Least Common Find the Least Common MultipleMultiple
5x5x2 2 + 15x + 10 and 2x + 15x + 10 and 2x22 – 8 – 8
Steps to Add/SubtractSteps to Add/Subtract
1.1. Factor the denominatorsFactor the denominators
2.2. Identify the LCD for multiplicationIdentify the LCD for multiplication
3.3. Multiply as neededMultiply as needed
4.4. Add/subtractAdd/subtract
5.5. SimplifySimplify
SimplifySimplify
33
5
45
12
x
x
xx
SimplifySimplify
84
3
124
12
x
x
xx
SimplifySimplify
153
4
1255
72
yy
y
SimplifySimplify
306
3
105363
22
x
x
xx
SimplifySimplify
633
12
693 22
xx
x
xx
x
HomeworkHomework
Re-teaching 9.5 AllRe-teaching 9.5 All
Day TwoDay Two
Complex FractionsComplex Fractions
A fraction that has a fraction in its A fraction that has a fraction in its numerator or denominator or bothnumerator or denominator or both
Ex:Ex:
Two methods to simplify:Two methods to simplify: 1. Multiply everything by the LCD1. Multiply everything by the LCD 2. Divide the numerator by the 2. Divide the numerator by the
denominatordenominator
11
13
12
x2-x
21
1
3
1
xx
x
yyx
Method 1: Multiplying by Method 1: Multiplying by LCDLCD
1.1. Find the LCD of Find the LCD of the ENTIRE the ENTIRE fractionfraction
2.2. Multiply Multiply everything by this everything by this LCD (notice that LCD (notice that the small the small fractions fractions disappear)disappear)
3.3. SimplifySimplify
45
31
y
x
xy
yx12
11
2. Dividing2. Dividing
1.1. Simplify the Simplify the numerator and numerator and denominatordenominator
2.2. Divide the Divide the numerator by the numerator by the denominatordenominator
45
31
y
x
y21
1
3
11
13
122
xx
xxx
HomeworkHomework
Practice 9.5Practice 9.5