Slope of a line

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Slope of a line

• Finding slope from
• 2 pts
• and graph

By Caleb Thompson Connie Harris
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Properties of the Coordinate Plane.
Quadrant II
Quadrant I
ordered pairs will be ( , )
ordered pairs will be ( - , )
( 0 , 0 )
Origin
X-axis
Also called horizontal axis
Quadrant IV
Quadrant III
ordered pairs will be ( , - )
ordered pairs will be ( - , - )
Y-axis
Also called vertical axis
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Remember how to plot and read ordered pairs?

• Name the ordered pairs for M, N, R, S

S
C
(1, 2)
D
R
Graph points A(6, -4) B(0, -5) C(-3, 1) D(5, 0)
(-5, 0)
M
N
(-3, -2)
(4, -2)
A
B
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3 ways to determine slope (m)

• From an equation you must solve for y first.
• From a line on the graph.
• From 2 points (the slope formula using two
  ordered pairs.)

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Solve for Y
Cant add or subtract these. Why? They are
not like terms.

• We want y by itself
• Move the x term (do the opposite or -)
• Move the term in front of y (do the inverse
  operation)
• Slope ½

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C
Positive Slopes
Negative Slopes
D
B
Expert slope
E
Intermediate slope
Beginner slope
A
Read line from left to right Going
uppositive Going down--negative
Going up--positive
Going downnegative
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Types of lines
Angles up Angles down Horizontal
Vertical
Slope is ______ Slope is ________
Slope is ______ Slope is _____
Undefined
Positive
Negative
Zero
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Find slope from a graph

• Pick two points on the grid
• Starting from left pt, count up or down on grid
• Write down that number in the numerator
• Count left or right to next point
• Write down this number in denominator
• This fraction is your slope

Going up is Positive
right is Positive
left is Negative
Going down is Negative
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Find slope from a graph

• Slope is a fraction
• How far did you go up/down?
• over (as in fraction bar)
• How far did you go left/right?
• Slope

Going up is Positive
right is Positive
left is Negative
Write this in your notes
Going down is Negative
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B
Read line from left to right Going
uppositive Going down--negative
A
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C
D
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E
Read line from left to right Going
uppositive Going down--negative
F
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Steps to find slope from 2 pts

• (x1, y1) (x2, y2)
• (2, 7) (8, 3)
• Formula
• (it will be given to you)

• Label your points
• (x1, y1) (x2, y2)
• Plug points into formula
• Simplify top and bottom, then divide the two
  numbers
• Calculator (y2 - y1) divide (x2- x2) enter

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Example 1

• (x1, y1) (x2, y2)
• (0, 4) (1, 2)

• Label your points
• (x1, y1) (x2, y2)
• Plug points into formula
• Simplify top and bottom, then divide the two
  numbers
• Calculator (y2 - y1) divide (x2- x2) enter

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Example 2

• (x1, y1) (x2, y2)
• (7, -4) (9, -1)

• Label your points
• (x1, y1) (x2, y2)
• Plug points into formula
• Simplify top and bottom, then divide the two
  numbers
• Calculator (y2 - y1) divide (x2- x2) enter

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Example 3-4

• (x1, y1) (x2, y2)
• (10, 5) (3, 5)

(x1, y1) (x2, y2) (-4, 2) (-4, 0)
3)
4)
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Let's look at these lines.
All VERTICAL lines have a slope that is undefined.
All HORIZONTAL lines have a slope of zero.
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Special Thanks

• Heather Nevins Smithville High School