Download 2.1 Use Integers and Rational Numbers Warm

2.1 Use Integers and Rational Numbers
Warm-up:
In Exercises 1 – 3, state an appropriate value for A, B, and C.
1.
2.
3.
0
A
0.5
-2
A
B
C
2
1
B
C
-1
A
B
C
In Exercises 4 and 5, locate points A, B, and C on a number line.
4.
A = -2, B = -0.5, C = 1.5
0
5.
1
1
1
A= −3 , B= −4
, C= -2
2
2
-4
-3
6. If three numbers were placed on a number line, how could you tell which was the least?
The greatest?
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1
7. How many numbers are between - 4 and -3? Explain.
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2
Goal • Graph and compare positive and negative numbers.
VOCABULARY
Opposite –
Absolute valueExample 1
Graph and compare integers
Graph −2 and −5 on a number line. Then tell which number is less.
Solution:
Graph the
point!
On the number line, _____. is to the left of_____. So, _____< _____
Example 2: Classify numbers. Tell whether each of the following numbers is a whole
number, an integer, or a rational number:
3, 1.7, −14, and - −1 .
2
Whole number?
Integer?
Rational Number?
3
1.7
-14
-½
Example 3 Order rational numbers
Temperature The table shows the low daily temperatures for a town over a five-day period.
Order the days from warmest to coldest.
Day
1
Temperatur 0°C
e
2
3
4
5
10°C
−2°C
5°C
−7°C
Step 1 Graph the numbers on a number line.
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From warmest to coldest the days are_________________________
3
Step 2
Read the numbers from left to right:
Now You Try It! Complete the following exercise.
1) Tell whether each of the following numbers is a whole number, an integer, or a rational
number:
0.8, −17, −5 3 and 2. Then order the numbers from least to greatest.
4
Whole numbers:
Rational numbers:
Integers:
Order:
Example 4 - Find opposites of numbers
a) If a = −4.8, then −a =________=_____.
b) If a= 5 , then −a =_____.
6
Example 5 - ABSOLUTE VALUE OF A NUMBER
The absolute value of a number is it’s distance from 0.
In words:
If x is _________________________________, then
x =x
If x is _________________________________, then
x =0
If x is _________________________________, then
x =x
In numbers:
5=
0=
−4 =
− −2 =
Now You Try It:
10 =
−10 =
− −10 =
2.9 =
4
3
=
7
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−