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Chapter 4
Algebra I and Concepts
Day 1, Section 4-1: Graphing in SlopeIntercept Form
Slope-Intercept Form: Any equation written in the
form y = mx + b
m:
b:
Which of the following are in slope intercept form?
Are any in standard form?
a) 4y = 2x + 6
b) y = 3x – 5
c) 2x – 5y = 12
Day 1, Section 4-1: Graphing in SlopeIntercept Form
Ex) Identify the slope and the y-intercept of the
following equations
a) y = ½x – 5
b) y = x + 7 c) 2x – 3y = 12
Ex) Write an equation of a line in slope-intercept
form, given the slope and the y-intercept
a) Slope: 4, y-intercept: -2 a) m = 6, b = 12
Day 1: Section 4-1
Write an equation in slope-intercept form for
the graph pictured
1)
2)
3)
Day 2, Section 4-1: Graphing in SlopeIntercept Form
Steps to Graphing an equation in slope-intercept
form. Ex) y = 2 x - 4
3
1) Plot the
________________
2) Count the slope
________ over _________,
And plot a second point
3) Draw a line connecting
The 2 points
Day 2, Section 4-1: Graphing in Slope-Intercept
Form
Slope Movement
Positive Numbers: UP/RIGHT
Negative Number: DOWN/LEFT
Ex) Graph the following equations using slopeintercept form method
a) y = -4 x + 2
b) y = 5x + 8
c) 5x – 3y = 15
5
Day 3: Section 4-1, Horizontal and Vertical
Lines
Graphing Horizontal Lines
Equations look like this:
y = a number
(there is NO x variable!)
To Graph:
1) Draw a horizontal line through
that number
Graph y = -2
Graphing Vertical Lines
Equations look like this:
x = a number
(there is NO y variable)
To Graph:
1) Draw a vertical line through
that number
Graph x = 6
Day 3: Section 4-1, Horizontal and
Vertical Lines
Graph the following lines. First determine if the line
is horizontal, vertical, or oblique.
1) y = 4
2) y = -2x + 4
3) x = -1
Day 1: Section 4-4, Parallel Lines
Parallel Lines – lines that do not intersect and have
the SAME SLOPE!
Ex) Use the 3 graphs to determine by looking if the
lines are parallel
Day 1: Section 4-4, Parallel Lines
Which of the following lines are parallel? Note:
you must be able to identify the slope in each
equation!
a) y = 2x + 3
b) 2x + y = 10
c) y - 2x = 5
d) y -1 = 2(x + 7)
e) 8x + 2y = 12
Day 2: Section 4-4 Perpendicular Lines
Opposite Reciprocals – 2 numbers whose product is
-1. Flip and switch the sign!
Perpendicular Lines - Lines that intersect to form a
right angle. Perpendicular lines have slopes that are
opposite reciprocals.
Ex) Find the opposite reciprocals of the following
numbers
a) 3
b) -5
c) ½
d) -¾
Day 2: Section 4-4, Comparing Lines
Determine if the lines are parallel,
perpendicular, or neither.
1) y = -2x
2) -3x + 4y = 8
2x + y = 3
3) 3x + 5y = 10
5x - 3y = -6
-4x + 3y = -6
4)
2x + 7y = -35
4x +14y = -42
Section 4-5, Scatterplots
Scatterplot – a graph showing the relationship
between a set of data with 2 variables
Section 4-5, Scatterplots
Ex) What kind of correlation does the graph
have? Describe its meaning.
Section 4-5, Scatterplots
Section 4-5: Scatterplots
Section 4-5: Scatterplots