Transcript Slide 1
Do Now 12/1/11
Copy HW in your planner.
Text
p. 120, #10-38 evens
In your journal, estimate what fraction of your
day you spend on the following: school,
eating, traveling (by car or bus), sleeping,
extra-curricular activities. Then determine
how much “spare time” you have each day.
Objective
SWBAT add and subtract fractions.
Section 3-5 “Adding and Subtracting Fractions”
Adding Fractions with Common Denominators
To ADD fractions with common denominators, add
their numerators together. Simplify if necessary.
Add the numerators
a b ab
c c
c
2 3
7 7
2 3 5
7 7 7
Subtracting Fractions with Common
Denominators
To SUBTRACT fractions with common
denominators, subtract their numerators. Simplify if
necessary.
Subtract the numerators
a b a b
c c
c
5 1
6 6
4 2
6 3
Try It Out!!
Solve
5 2
8 8
5 2 7
8 8 8
5 2
12 12
5 2
3 1
12 12 12 4
“Opp-opp”
6 5
18 18
Put the negative
sign with the
numerator.
6 5 1
18 18 18
3 2
5 5
3 2
5 5
3 2 5
1
5 5 5
Fractions with Different Denominators
To ADD or SUBTRACT fractions with different
denominators follow these steps:
1. Rewrite the fractions using a common denominator.
2. Add or subtract the numerators.
2 1
5 7
What is the common denominator?
5: 5, 10, 15, 20, 25, 30, 35, 40
7: 7, 14, 21, 28, 35, 42
2 ?
5 35
2 7 14
5 7 35 Equivalent
1 ?
7 35
1 5 5
7 5 35
14 5 19
35 35 35
fractions
Try It Out!!
Solve
1 2
7 3
3 14
21 21
3 14 17
21 21 21
7 1
12 4
7 3
12 12
Don’t forget your
integer rules.
“Opp-Opp”
-7 + (-3) = -10
7 3 10
12 12
12
10
5
12
6
Try It Out!!
Solve
6 1
11 4
24 11
44 44
24 11
35
44 44
44
4 2
5 20
16 2
20 20
16 2
20 20
18
9
20
10
Don’t forget your
integer rules.
“Opp-Opp”
-16 + (-2) = -18
1 3 1
3 7 9
1 3 1
3 7 9
24 11
44 44
24 11
35
44 44
44
1 3 1
3 7 9
16 2
20 20
16 2
20 20
18
9
20
10
Don’t forget your
integer rules.
“Opp-Opp”
-16 + (-2) = -18
NJASK7 Prep
Homework
Text
p. 228, #10-28 evens, 38-44 evens