# Investigation 2

Document Sample

```					    Investigation 2

Introducing
Addition and Subtraction
of Integers
New Vocabulary

•STEPS for
solving a problem
Problem #1
John has 8 video games and
his friend has 5. Together
they have 8 + 5 = 13 games.

How could you model this
problem using chips?
Problem #2
At a desert weather station, the temperature
at sunrise was 10 degrees Celsius. It rose
25 degrees Celsius by noon. The
temperature at noon was 10 +25 = 35
degrees Celsius.

How could you use a number line
to model this problem?
Adding Integers! READY? OK!
• If the signs are the same, you add the
numbers and keep the same sign!
• If the signs are the same, you add the
numbers and keep the same sign!
• If the signs are different, you find the
difference and keep the bigger sign!
• If the signs are different, you find the
difference and keep the bigger sign!
Integer Operations…to the tune of
Row, Row, Row your boat.
Same signs add and keep
Different signs subtract.
Take the sign of the larger number
Then you’ll be exact.
Multiply and Divide,
It’s an easy task.
Same signs positive
Different signs are not.
Adding Integers
Are the signs the
same?

Find the difference
Add the numbers and       Between the numbers
keep the common sign.      And keep the sign of
The larger number.
2.1 A
1. Find the sums in       Group 1
2+8
each group.
-3 + -8
2. Describe what the      20 + 25
examples in each       -24 + -12

group have in
Group 2
common.
8 + -12
3. Describe an            -3 + 2
algorithm for          14 + -23

adding integers to     -11 + -13

each group.
Now Let’s Practice.
1) -5 + 10 =________     11) -12 + 6 = ________
2) 8 + -18 =________     12) 65 + 5 = ________
3) 5 + (-9) =________    13) 75 – 25 = ________
4) 2 + (-2) =________    14) -50 + (-50) = _____
5) -18 + 20 = _______    15) -22 + 5 = ________
6) -11 + (-4)= _______   16) -40 + 20 = _______
7) 20 + (-13) = ______   17) -36 + 44 = _______
8) -25 + 20 = _______    18) -96 + 54 = _______
9) 20 + (-30) = ______   19) -84 + (-44) = _____
10) -26 + (-4) = _____   20) 72 + (-60) = ______
Complete B through D
in your textbook on
page 24 in the
Accentuate the
Negative section.
Challenge

Compute the following:

-5 + 7 + (-14) + (-9)
Investigation 2.2
Let’s review!
Example 1
Kim had 9 CD’s. She sold 4
CD’s at a yard sale. She
only has 9-4=5 of those CDs
left.

In this example, you are
taking away
objects from a set of objects.
Group 1
12 - 8
1.Find the differences in    -5 – (-7)

each group.                -4 – (-2)
2-4
2.What pattern do you
Group 2
see in each group?
12 – (-8)

3. Describe an algorithm     -5 – 7
-4 – 2
for subtracting integers
2 – (-4)
in each group.
Try these…
1. -1 – 3 = _____

2. -1 – ¾ = _____

3. -1 ½ - (-2) = _____

4. - 1 ½ - (-3/4) = _____
Are the expressions equal?
Think-Pair-Share…

1. -2 – 3 ___ 3 – (-2)

2. 12 – (-4) ___ -4 – 12

3. -15 – (-20) ___ -20 – (-15)
Let’s Practice
1.    5 - 12
2.    -2 - 6
3.    6- (-16)
4.    -11- (-7)
5.    -13- (-12)
6.    -14 – (-14)
7.    11 – (-6)
8.    9 – 17
9.    -18 – (-12)
10.   -20 - 7
•   32-40
•   28 – (-16)
•   -39 – (-13)
•   35 – 10
•   -32 – (-37)
•   50 – 99
•   64 – 101
•   -5 – 5
•   17-7
•   9 – (-11)
Summary
Without computing the answers, predict
how the answers in each pair will
compare. Will the answers be the same
or different? IF they are different, which
will be greater? Explain your answer.

1. -7 + (-8) and -7 – 8

2. -12 – (-4) and -4 – (-12)

```
DOCUMENT INFO
Shared By:
Categories:
Stats:
 views: 12 posted: 8/13/2010 language: English pages: 25
How are you planning on using Docstoc?