Download Evaluating Expressions with multiplying and dividing integers

Math Journal 8-13-14
Find the perimeter of the trapezoid:
4x ft
3x ft
3x ft
60x in
UNIT 1 DAY 3: EVALUATING
EXPRESSIONS WITH
MULTIPLYING AND DIVIDING
INTEGERS
Essential Questions: What are the rules for multiplying
and dividing integers? How do you substitute a number
for a variable?
Vocabulary
Product: the answer obtained by multiplying two
or more quantities.
Factor: the numbers and variables that are
multiplied in an expression.
Quotient: the answer obtained by dividing two or
more quantities.
Multiplying and Dividing Integers
To figure out the signs when multiplying or
dividing integers, use the following rules:
Same Signs: Positive
Different Signs: Negative
If you have more than two negative factors…
Even # of negatives = positive
Odd # of negatives = negative
Example 1
a)
-8(2)
b)
-5(-7)
-16
c)
12(9)
108
35
d)
(1/2)(-18)
-9
Example 2
a)
b)
6
c)
-10
d)
-9
7
Evaluating Expressions
To evaluate an expression:
1) Substitute each variable with the given
number.
2) Simplify the expression to a single value.
Example 3
Evaluate the following expressions when a = 12, b = -3,
and c = 24.
a)
c)
6/b
b)
a/b
6/-3
12/-3
-2
-4
c/-b
24/3
8
d)
b(c/a)
-3(24/12)
-3(2)
-6
Example 4
h
The plane’s height above the ground (in thousands of
feet) equals the distance from the airport (in miles) that a
plane should begin descending divided by 3.
height = distance/3
If a plane is 30 miles from the airport when the pilot
begins to land the plane, what is the plane’s height
above ground in thousands of feet?
height = 30/3
The plane is 10 thousand
feet above the ground.
Summary
Essential Questions: What are the rules for multiplying
and dividing integers? How do you substitute a number
for a variable?
Use 1 minute to write 2 sentences answering the
essential questions.