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Lesson 4-1 Warm-Up
ALGEBRA 1
“Graphing on the Coordinate
Plane” (4-1)
What is the coordinate
coordinate plane (also called a grid): two number lines that intersect (cross)
at right angles(3-1)
plane and how do you
graph coordinates on
it?
x-axis: the horizontal number line
y-axis: the vertical number line
origin (means “beginning”): the point at which the two number lines cross
quadrant (means “one of four parts”): one of the four sections made by the
intersection of the two axes
ordered pair: two numbers called the x-coordinate and y-coordinate that that
identify the location of a point on the coordinate plane
The x-coordinate tells you how far to move right (+) or left (-) from the origin
and the y-coordinate tells you how far to move up (+) or down (-) from the
origin.
ALGEBRA 1
“Graphing on the Coordinate
Plane” (4-1)
How do you name a
Always start at the origin. Then, count the number of units (jumps) right (+) or left (-)
to identify the x(3-1)
– coordinate. From there, count the number of units up (+) or down
point on a grid?
(-) from the x-axis to identify the y – coordinate
Example: Name the following coordinate.
Start at the origin. Move 2 units to the left (x = -2). Then move 3 units down (y = 3). The coordinates of z are (-2, -3)
How can you determine
what quadrant a
coordinate is in?
You can easily determine the quadrant a coordinate is in by looking at the signs.
Quadrant I (1) is (+, +), Quadrant II (2) is (-, +), Quadrant III (3) is (-, -), and
Quadrant IV (4) is (+, -). A point that is on an axis is not considered to be in a
quadrant.
ALGEBRA 1
Graphing on the Coordinate Plane
LESSON 4-1
Additional Examples
Graph the points on the same coordinate plane.
a. P(–1, 3 )
Move 1 unit to the left of the origin. Then move 3 units up.
b. Q(0, –2)
Since the x-coordinate is 0, point Q is on the y-axis.
Move 2 units down from the origin.
ALGEBRA 1
Graphing on the Coordinate Plane
LESSON 4-1
Additional Examples
In which quadrant or on which axis would you find
each point?
a. (5, 3)
Since the x-coordinate is positive and the y-coordinate
is positive the point is in Quadrant I.
b. (0, –7)
Since the x-coordinate is 0, the point is on the y-axis.
ALGEBRA 1
Graphing on the Coordinate Plane
LESSON 4-1
Additional Examples
Name the coordinates of each point in the graph below.
a. M
Move 1 unit to the right of the origin. Then move 4
units down. The coordinates of M are (1, –4).
b. N
Move 3 units to the left of the origin. Since N is directly to the left
of the origin, the y-coordinate is 0. The coordinates of N are (–3, 0).
ALGEBRA 1
Graphing on the Coordinate Plane
LESSON 4-1
Lesson Quiz
Use the graph for 1–9.
Name the coordinates of each point.
1. A (–3, –3)
2. B (– 2, 1)
3. C (2, 0)
4. D (3, 2)
Graph each point on the coordinate plane.
5. E (–1, 3)
6. F (–3, –1)
7. G (–1, –3)
8. H (1, –3)
9. In which quadrant is point E? II
ALGEBRA 1