Download Multiplying /Dividing Integers

Multiplying Integers
3.05
Math 123A
Warm-Up
1. Find 3 – (- 5).
__________________
2. Find (-6) - (-2).
____________________
1. Find 4 + (-2).
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____________________
EXPLAIN in your words the rule
for multiplying and dividing
integers.
Rules
 Same signs…..postive
 Opposite signs….negative
 Examples:
2*3=6
-2*-3=6
2*-3=-6.
-2*3=-6
Let’s Sing a Song!
Multiplying Integers Song
(sing to “Dead Bones” tune)
Verse 1
A negative times a negative is a, (um) positive
A negative times a positive is a, (um) negative
A negative times a negative is a, (um) positive
These are the rules for signs.
Verse 2
If you have the same signs, you get a positive,
But if they’re different, you get a negative,
If you have the same signs, you get a positive,
Yes, these are the rules for signs.
Breakout Rooms
 Your Choices:
 A – Feel like you need a little more practice? This is the room
for you!
 In this room, use the arrows to find an empty page and claim it
with your first initial and last name. Work with a partner to solve
on the whiteboard.
 B – Do you feel like you’ve got this? Go ahead and try the
quizzes 3.05 and 3.06
 Be sure you put your first initial and last name on the page in this
room so I’ll know where your working.
 C – Are you an integer pro? Come to this room for a
challenge!
 Work together with the participants in his room to solve the
challenge!
 D – Need more help? I’ll be in the main room 
Directions: Look at each problem. Write your answer on the lines provided.
1. -6 x -9
______________
2. 15 x -4
______________
3. -25 x -5
______________
4. -16 x 4
______________
5. 6 x 3
______________
6. -4 x -2
______________
7. 5 x -2
______________
8. 2 x 7
______________
First name: Complete
Evens, check odds
Second Name: Complete
Odds, check evens.
Be sure to check each othe
Work, be able to explain
Your work, and put your
First initial and last name on
This page.
Directions: Look at the word problem. Show your work in the box provided.
9. A temperature that is first recorded at -2 degrees Fahrenheit
falls three degrees per hour. What is the temperature at the end
of four hours?
Completing the Quizzes? Put
your first initial and last name,
and then log into our course. 
Challenge
Dividing Integers and
Reciprocals
Students will divide integers and display their
knowledge of reciprocals.
Multiplying /Dividing Integers
Ex. –3 + (–3) + (–3) + (–3)
= –12
This is the same as 4 • (–3) = –12
You can see that a positive times a negative integer gives a negative
product.
+ • –
=
–
– • +
=
–
– • –
=
+
+ • +
=
+
Ex. a. 5(–11)
– 55
What about 5(–11)(2) ?
=
–55 • 2
= –110
Rule for multiplication:
An odd amount of negatives gives a negative product.
An even amount of negatives gives a positive product.
Division of Real Numbers
The product of a number and its reciprocal is 1.
Here are some examples of reciprocals:
1/4 and 4 –5/2 and –2/5
–9 and –1/9
To divide a number, you can multiply by its reciprocal.
b ÷ a = b • 1/a
So the rules for dividing real numbers are the same as multiplying real
numbers.
+ ÷ –
=
–
– ÷ +
=
–
– ÷ –
=
+
+ ÷ +
=
+
Example:–24 ÷ (–3)
negative ÷ negative = positive
8
Example:
28
–7
Let’s see what you know…
How will this look?
Exit Ticket
 Study Island: Solve Equations and Inequalities
 Open a different window and practice in Study Island if
you have not completed it yet.