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Friday, October 14th
• Please write down Homework and complete Warm UP
1. Simplify 9 + (-10) – 21
2. Simplify -24 – (-27) x (-2)
Decimal Packet• + and – due next Wednesday• x and ÷ due next Friday
WHY? Our next unit is rational numbers…decimals, fractions, negatives, positives
Subtracting decimals
Adding Decimals*When you subtract decimals you
have to: line up your decimals and add in your zeroes
*Remember that every number is a decimal, even if a decimal point isn’t written. Example: 5 is really 5.0
A little Riddle….
“Line up your decimals, add in your zeroes, find the sum, don’t be a bum…..line up your decimals, add in your zeroes, now it’s time to subtract, don’t get this out of wack”
Unit #1Fractions
+, -, x, and ÷
+ and - RuleWhen you add and
subtract fractions they must have the same denominator
You only add or subtract the Numerator
Review: Simplest Form
Your answers always must be in simplest form
Simplest form=no common factors
Think? Can I divide both numbers by anything?
Example:
8/14Can I divide 8 or 14 by anything?
2So 4/7
Homework Answers
Todays Mission
Adding and subtracting with unlike
denominators
How do we add when we don’t have common
denominators?!?
1 3
2 4
Fractions that represent the same value are equivalent.
Remember!
To add or subtract unlike fractions, first rewrite them
as equivalent fractions with a common denominator.
• You can use any common denominator or the least common denominator to add and subtract unlike fractions.
• The least common denominator (LCD) is the least common multiple of the denominators.
1 3
2 4
11
12__ 3
8__
–11
12__ 3
8__
–22
24__ 9
24__
Multiples of 8: 8, 16, 24, … The LCD is 24.
Write equivalent fractions with a common denominator.
Subtract. 13
24__
Multiples of 12: 12, 24, …
4
7__ 1
3__
–4
7__ 1
3__
–12
21__ 7
21__
Multiples of 3: 3, 6, 9, 12, 15, 18, 21, …The LCD is 21.
Write equivalent fractions.
Subtract. 5
21__
Multiples of 7: 7, 14, 21, …
Add or subtract. Write each answer in simplest form.
1. + 2. –
3. – 4. +
5. Bonnie is making oatmeal bars and the recipes calls for
cup of brown sugar. If she has cup of brown sugar, how
much more does she need?
3
8__ 1
6__ 1
2__ 1
8__
5
12__ 1
6__ 1
6__ 1
8__
3
4__
1
3__
13
24__ 3
8__
1
4__ 7
24__
5
12__ cup
You TryComplete all 8 problems on
your notes
When you are done, raise your hand and then help others
around you
