Chapter 8 ‐ Slopes & Equations of Lines
8.1 The Slope of a Line
SLOPE ‐ rise or m = y2 ‐ y1
x2 ‐ x1
run
Positive
4 TYPES OF SLOPE
Zero
Negative
(1,2) (3,3)
(2,3) (5,1)
No Slope
(­2,­2) (1,­2) (2,1) (2,­2)
-lowercase m stands for slope
-uppercase M stands for midpoint
1
2
y‐intercept
where the graph
crosses the y‐axis
(x=0)
x‐intercept
where the graph
crosses the x‐axis
(y=0)
ex: Find the slope between a y-intercept of -1 and an
x-intercept of 3.
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8.2 The Equation of a Line
***3 points (A,B,C) lie on the same line if the slope between AB is the same as slope between BC***
4
There are two formulas we can use the write the equation of a line
Point‐Slope Form
y ­ y1 = m(x ­ x1)
Slope‐Intercept Form
y = mx + b
d. Use slope­intercept form to write the equation of the line
5
6
Write the equation of the line that goes through (1,­2) and (5,10)
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pg 295 #16‐19
and pg 299 #4‐15
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