3.6: Lines in a Coordinate Plane
Yourmother
motherwas
wasaahamster
hamsterand
andyour
yourfather
fathersmelt
smeltof
ofelderberries.
elderberries.
Your
-French Soldier
Algebra 1 Review
Slope of a Line: Ratio of its vertical change to the corresponding
horizontal change (“rise over run”)
y
Rise y 2  y1
Slope =

Run x 2  x1
x2  x1
P2 (x2, y2 )
y2  y1

P1(x1, y1)



x

Algebra 1 Review
Slope of a Line: Ratio of its vertical change to the corresponding
horizontal change (“rise over run”)
y
Rise y 2  y1
Slope =

Run x 2  x1
P2 (11,6)
P1(2,3)


x

Algebra 1 Review
Find the slope of the line below.
Algebra 1 Review
Graph the line that contains the point (2,1) and the slope of…
1
1) m 
4



2) m  2
3) m  0
Forms of a Line
Slope-Intercept Form: y  mx  b
m = slope b = y-intercept
 Ax  By  C
Standard Form:
A,B are integers ≠ 0 and A > 0

1
Ex : y  x  3
2


Point-Slope Form: y  y1  m(x  x1)
m = slope (x1,y1) = point on line
Ex : x  2y  6
1
Ex : y  3  (x  0)
2
Graphing Lines in Slope-Intercept Form
3
Graph the line y  x  2 .
4

Graphing Lines in Standard Form
Graph the line 2x + 3y = 6.
Method 1: Transform to
Slope-Intercept Form
Graphing Lines in Standard Form
Graph the line 2x + 3y = 6.
Method 2: Find intercepts
Using Point-Slope Form
Write an equation in point-slope form of the line through point
P(-1,4) with slope 3.
Using Point-Slope Form
Write an equation in point-slope form of the line through the
points A(-2,3) and B(1,-1).
Horizontal and Vertical Lines
Let’s take a look at the vertical line and horizontal line through
the point (-3,1).
Horizontal Lines
Slope = 0
Equation: y  b
Vertical Lines

Slope Undefined
Equation: x  a
Horizontal and Vertical Lines
Write equations for the horizontal line and the vertical line that
contain the point (2,-5).
3.6: Lines in a Coordinate Plane
HOMEWORK:
3.6: #2-36 even
Evilwill
willalways
alwaystriumph
triumphover
overgood
goodbecause
becausegood
goodis isdumb.
dumb.
Evil
-Dark Helmet