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Section1 2

The document covers concepts from Algebra 1, focusing on subsets of real numbers, the number line, opposite numbers, and absolute values. It includes definitions, examples, and a formula for finding the midpoint of a segment. Additionally, it provides homework assignments for practice.

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kelvin
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7 views14 pages

Section1 2

The document covers concepts from Algebra 1, focusing on subsets of real numbers, the number line, opposite numbers, and absolute values. It includes definitions, examples, and a formula for finding the midpoint of a segment. Additionally, it provides homework assignments for practice.

Uploaded by

kelvin
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PPTX, PDF, TXT or read online on Scribd
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Algebra 1

Section 1.2
Lesson Opener
What is the most specific
subset of the real numbers to
which each number belongs?
–9 integers
π irrational numbers
3.5 rational numbers
Lesson Opener
What is the most specific
subset of the real numbers to
which each number belongs?
1.121231234… irrational numbers
0 whole numbers
The Number Line
The number line extends
without limit in both directions
Origin: the point at zero
Positive numbers are to the
right of zero
Negative numbers are to the
left of zero
The Number Line
A point on the number line is
called the graph of a number
Named with a capital letter
The number associated with
the point is called a coordinate
The Number Line
Numbers increase in value
from left to right
–3 > –5
2<4
The Number Line
Number lines can be divided
into units of one, or units
greater or smaller than one
Number lines can be drawn
horizontally or vertically
Definition
Opposite numbers: numbers
that are the same distance
from zero but are on opposite
sides of zero
Example 3
State the opposite of each number:

a. 12 –12
b. –37 37
c. –4.7 4.7
π π
d. –
2 2
Definition
The absolute value of a
number, denoted |x|, is the
number of units (distance)
between zero and the
number’s graph on a number
line
Example 4
Find each absolute value.
a. |4| 4
b. |–3| 3

Distances are never negative;


therefore, absolute values are
never negative
Example 5
Simplify.
a. |74| – |–24| b. |82 – 31|
= 74 – 24 = |51|
= 50 = 51
Formula
The coordinate of the
midpoint, m, of a segment is
the average of the endpoints’
coordinates
a+b
m=
2
Homework:

pp. 10-11

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