Embed Size (px)
Citation preview
Wednesday, October 20 (Blue)Thursday, October 21 (Gold)
Objective Students add and subtract fractions and mixed numbers
8
3
• Fill in planner• Today’s Assignment (Practice 5-3)
• Bell Work• Compare the fractions using <,>, or =
4
1
3
2
10
9
8
7
6
3
10
5
3
2
4
3
Adding Fractions with common denominators
8
4
8
3
8
7
Just add the numerators!
Adding Fractions with different denominators
Problem:
You can’t add fractions with different denominators.
Solution: Turn fractions into equivalent fractions with a
common denominator, preferably the LCD!
Finding the Lowest Common Denominator
• The lowest common multiple of two numbers is the lowest number in BOTH lists of multiples
3
1
2
1
Multiples of 2 are 2, 4, 6, 8, 10……
Multiples of 3 are 3, 6, 9, 12, ………
What is the lowest common multiple?
Example 1
Finding the Lowest Common Denominator
• The lowest common multiple of two numbers is the lowest number they will BOTH divide into
3
1
2
1
2 divides into 2, 4, 6, 8…..3 divides into 3, 6, 9….
What is the lowest number 2 and 3 both divide into?
+The Lowest Common Multiple of 2 and 3 is 6 so turn all fractions into sixths
6
3
3
3
2
1
You can’t add fractions with different denominators
Special form of 1
3
1
2
1
6
2
2
2
3
1
6
5
6
2
6
3
10
9
10
4
10
5
5
2
2
1
Lowest common denominator is 10 so make all fractions tenths
Example 2
4
1
3
1
Turn both fractions into twelfths
12
7
12
3
12
4
Example 3:
Variable Expressions
6
5
8
1 x
Example 4
46
45
38
31
x
24
203 x
Variable Expressions
mm 3
4
3
2
Example 5
m3
42
m3
2
Variable Expressions
52
yy
Example 6
25
2
52
5
yy
10
7y10
2
10
5 yy
Adding Mixed Numbers
Find the sum.1
4
9
+ 31
9
1. Rewrite the fraction using LCD if denominators are different.
2. Add or subtract the fractions,
then the whole numbers.3. Simplify if possible.
45
9 In this problem, the denominators are the same, so begin with step 2.
Let’s Do More Examples!
14
9
31
3+ =9
3
X 3
X 3
47
9
47
8
51
4+ =8
2
X 2
X 2
99
8
= 11
8
10
1
8Add the whole numbers.
Example 8 Example 9
