Intercepts

1
Intercepts

• Objective To graph a linear equation using the
  x- and y-intercepts or using the slope and
  y-intercept.

2
5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5, 3)
3
5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5, 3) 5/9
4
5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5,
3) 5/9 2. H(1, 4), S(5, -2)
5
5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5,
3) 5/9 2. H(1, 4), S(5, -2) -3/2
6
5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5,
3) 5/9 2. H(1, 4), S(5, -2) -3/2 3. G(0,
7), B(2, -7)
7
5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5,
3) 5/9 2. H(1, 4), S(5, -2) -3/2 3. G(0,
7), B(2, -7) -7
8
5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5,
3) 5/9 2. H(1, 4), S(5, -2) -3/2 3. G(0,
7), B(2, -7) -7 4. J(0, 0), W(4, -4)
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5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5,
3) 5/9 2. H(1, 4), S(5, -2) -3/2 3. G(0,
7), B(2, -7) -7 4. J(0, 0), W(4, -4) -1
10
5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5,
3) 5/9 2. H(1, 4), S(5, -2) -3/2 3. G(0,
7), B(2, -7) -7 4. J(0, 0), W(4, -4) -1 5.
R(-4, -4), F(-5, -3)
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5-Minute Check
Find the slope of the line that contains each
pair of points. 1. C(-4, -2), D(5,
3) 5/9 2. H(1, 4), S(5, -2) -3/2 3. G(0,
7), B(2, -7) -7 4. J(0, 0), W(4, -4) -1 5.
R(-4, -4), F(-5, -3) -1
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Intercepts
Learning the Concept The graph of a linear
function may cross either the x-axis, the y-axis,
or both axes.The x-intercept is the x-coordinate
of the point where the graph crosses the
x-axis.The y-intercept is the y-coordinate of
the point where the graph crosses the y-axis.
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Intercepts
The line graphed below crosses both axes.
x-intercept
The line graphed crosses the x-axis at (5, 0).
Therefore the x-intercept is 5. Note that the
corresponding y-coordinate is 0.
y-intercept
y-intercept
The line crosses the y-axis at (0, 2). So the
y-intercept is 2. Note that the corresponding
x-coordinate is 0.
x-intercept
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Intercepts
From the previous slide, we learned that the
y-coordinate for the point of the x-intercept is
0. We also learned that the x-coordinate for the
point of the y-intercept is 0. So, to solve for
the x-intercept for an equation, we let the
y-value be 0 and then solve for x. Also to solve
for the y-intercept for an equation, we let the
x-value be 0 and then solve for y.
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Intercepts
Example 1Find the x-intercept and y-intercept
for y 3/2x 6. Then graph the equation using
the x- and y-intercepts.
x-intercepty 3/2x 6 0 3/2x 6 0 6
3/2x 6 6 6 3/2x 62/3 3/22/3x 4
xThe x-intercept is 4. The ordered pair is (4,0).
y-intercepty 3/2x 6 y 3/20 6 y
6 The y-intercept is -6. The ordered pair is
(0,-6).
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Intercepts
The points were (4, 0) and (0, -6). We now graph
the intercepts and draw the line that contains
them.
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Intercepts
The points were (4, 0) and (0, -6). We now graph
the intercepts and draw the line that contains
them.
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Intercepts
The points were (4, 0) and (0, -6). We now graph
the intercepts and draw the line that contains
them.
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Intercepts
The points were (4, 0) and (0, -6). We now graph
the intercepts and draw the line that contains
them.
We can check our work by selecting a point on the
line, (2,-3) to see if we are correct. y 3/2x
6 3 3/2(2) 6 3 3 6 3 3
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Intercepts
If we already have a line on the graph, how will
we be able to determine the x- and y-intercepts?
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Intercepts
If we already have a line on the graph, how will
we be able to determine the x- and y-intercepts?
What are the intercepts?
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Intercepts
If we already have a line on the graph, how will
we be able to determine the x- and y-intercepts?
What is the slope of this line?
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Intercepts
Assignment 18 42E, 43 - 53 all. Pages 409 410