+ Fractions: Addition & Subtraction Algebra Seminar 2012-2013.
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Transcript of + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.
![Page 1: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/1.jpg)
+
Fractions: Addition & Subtraction Algebra Seminar 2012-2013
![Page 2: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/2.jpg)
Two Fractions can be combined easily when they have a common denominator.
8
7
8
5+
12
43
12
55 +
5
10+
410
13
8+ 4
28
![Page 3: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/3.jpg)
+
Def. Common Denominator- A number that all of the denominators divide into evenly.
![Page 4: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/4.jpg)
+Common Denominator (similar to LCM)
A number all original denominators divide into evenly
12 is a common denominator because 3 and 4 both divide 12 evenly.
3
2
4
3
![Page 5: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/5.jpg)
Least Common Denominator (same as LCM)
To find the least common denominator
* Write the times table list for each denominator
* The smallest number that is in all rows is the least common denominator
![Page 6: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/6.jpg)
+Least Common Denominator
To find the least common denominator• Write the times table list for each denominator• The smallest number that is in all rows is the
least common denominator
![Page 7: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/7.jpg)
+The least common denominator is: 24!!!
so5
6+
34
+78
=2024
+1524
+2124
=5624
=72
=312
![Page 8: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/8.jpg)
+Practice - Find the common denominator for these fractions.
2/3 + 3/5
¾ + 7/12
2/5 + 3/8 + 7/10
![Page 9: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/9.jpg)
What if the denominators do NOT match? If the denominators do not match, you must
find the LCM to change them.
12
51
12
17
12
8
12
93
2
4
3
=
=+
=+5
8+
13
=
1524
+824
=2324
![Page 10: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/10.jpg)
+
Subtracting Fractions
![Page 11: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/11.jpg)
+Subtraction – the process is the same but you will subtract the numerators instead of adding them.
Squirt reminds you to:
1) Get a Common Denominator
2) Subtract
7
8−
34
=
78
−68
=18
![Page 12: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/12.jpg)
+Extra Practice
7
8−
14
=
5
6−
35
= 14
15−
39
=
7
10−
25
=
![Page 13: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/13.jpg)
+Subtraction
What is different about this problem? We have a mixed number!
Lets change them to improper
fractions!
42
5−2
35
=
22
5−
135
=9
5=1
45
![Page 14: + Fractions: Addition & Subtraction Algebra Seminar 2012-2013.](https://reader035.fdocuments.us/reader035/viewer/2022062407/56649d005503460f949d1a08/html5/thumbnails/14.jpg)
Subtraction Practice
73
4−2
56
=
16
10−
46
=
32
4−1
35
=