TEACHER: Mr. Landry ROOM NUMBER: 111
landrg@portlandschools.org
GENERAL TOPIC
X AND Y INTERCEPTS

WHAT I WILL ASSUME

I am going to assume that you can plot a set of ordered pairs as points on a Cartesian Coordinate System. If you are unsure how to plot ordered pairs please go the the column on your right and see the EXTRAS area.
COMMENT: You have also seen yintercepts(vertical intercepts). But I need to review this for the upcoming sections.

VERTICAL INTERCEPTS AND HORIZONTAL
INTERCEPTS

In figure 1 below you can see a line with two points on it. The
line intersects the x axis at the point (4,0) and intersects the y axis at
the point (0,2).
The x value, 4, of the point on the line that intersects the x axis is called the xintercept or the horizontal intercept. Some math books will say the x intercept is (4, 0).
The y value, 2, of the point on the line that intersects the y axis is called the yintercept or the vertical intercept. Some math books will say the y intercept is (0, 2).
We are reviewing these concepts as it will be very important that you
understand how to name the x and y intercepts, also called the horizontal and
vertical intercepts, in some upcoming exercises.
figure 1
If the axes are named by other variables than x and y then you would not use
the words x intercept or y intercept as we did above. See figure 2 below. In
this case I would say the h intercept is 3 and the s intercept is 2.
figure 2
example 1) Name the x and y intercept from the figure below.
ans: The x intercept is 5 and the y intercept is 3.
example 2) Name the z intercept(vertical intercept) and w intercept(horizontal
intercept) from the figure below.
ans: The w intercept is 1 and the z intercept is 3.
example 3) Name the vertical and horizontal intercept from the figure below.
ans: The vertical intercept(kintercept) is 4.5 and the horizontal
intercept(q intercept) is 5.1.

HOW TO FIND VERTICAL AND HORIZONTAL
INTERCEPTS
WITHOUT GRAPHING

If you have an equation of a line in slope intercept form then you can find the x intercept and y intercept very easily. I will do 3
examples.
example 1) Given the equation of the line in slope intercept form determine the x and y intercept, then graph using the x and y intercept.
ans: You know the y intercept(vertical intercept) is 6 based
on the slope intercept form of a line.
Please note that 6 is also called the vertical intercept.
To get the xintercept all you have to do is set y equal to 0 and solve for x.
OR
This is the x intercept
Please note that 2 is also called the horizontal intercept.
Here is the graph:
example 2) Given the equation of the line in slope intercept form determine the x and y intercept, then graph using the x and y intercept.
ans: You know the y intercept(vertical intercept) is 8 based
on the slope intercept form of a line.
To get the xintercept all you have to do is set y equal to 0 and solve for x.
OR
This is the x intercept
Here is the graph:
example 3) Given the equation of the line in slope intercept form determine the t and s intercept, then graph using the t and s intercept.
answer: The s intercept is 10. This is also called the
vertical intercept.
To find the t intercept set s=0 and solve for t.
or
is the t intercept
Here is the graph:
HOMEWORK
DIRECTIONS  GIVEN THE FOLLOWING EQUATIONS IN SLOPE INTERCEPT FORM
DETERMINE THE VERTICAL AND HORIZONTAL INTERCEPT THEN GRAPH THE EQUATION USING
THE INTERCEPTS.

BACK TO ALGEBRA 1 PART 2 CURRICULUM

EXTRAS

... MULTIPLICATION AND PARENTHESES
 PRIME FACTORIZATION
... ORDER OF OPERATIONS
PART 1: PART 2 : PART 3
... MONOMIAL,TERMS AND FACTORS
... THE WORLD OF EXPONENTS
... ADDING SIGNED NUMBERS ON A NUMBER LINE
...VARIABLES: 4 PARTS
PART 1  PART 2  PART 3  PART 4
... ABSOLUTE VALUE
... USING DUDE TO ADD INTEGERS
... USING DUDE TO SUBTRACT INTEGERS
... CARTESIAN COORDINATE SYSTEM:
PART 1 : PART 2 : PART 3 : PART 4 : PART 5
more to come
GEOGEBRA EXERCISES: ADDING LIKE TERMS
 ADDING LIKE TERMS 1
 ADDING LIKE TERMS 2
GEOGEBRA EXERCISES: EVALUATE AN ALGEBRAIC EXPRESSION
 EVALUATE ALGEBRAIC EXPRESSION 1
 EVALUATE ALGEBRAIC EXPRESSION 2
 EVALUATE ALGEBRAIC EXPRESSION 3
...GEOGEBRA EXERCISE: SLOPE OF A LINE
...GEOGEGRA EXERCISE: BEST FIT LINE

TI 83/84

 BASIC GRAPHING  PART 1 : more to come
