swbat… write lines in slope-intercept form wed, 2/20/10 agenda 1.warm-up (10 min) 2.notes on slope...
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SWBAT… Write lines in slope-intercept form Wed, 2/20/10
Agenda1. Warm-up (10 min)2. Notes on slope intercept – 4 examples (30 min)3. Exit slip (5 min)
WARM-UPhttp://nlvm.usu.edu/en/nav/frames_asid_332_g_4_t_2.html?from=category_g_4_t_2.html
HW#3: Writing equations in slope-intercept form
Slope-intercept form:Slope-intercept form:Slope-intercept form:Slope-intercept form:
What is the slope? ____________
2 1y x Now look at the equation below……
What is the y-intercept? ____________
Given y = ½x + ¾, what is the slope and the y-intercept?
m = ½b = ¾
Given y = ½x – ¾, what is the slope and the y-intercept?
m = ½b = -¾
Given y = -½x – ¾, what is the slope and the y-intercept?
m = -½b = -¾
• y = mx+ b is an equation that defines a line
• A line has two characteristics1. Slope2. Points that fall on the line
Converting linear Converting linear equations into Slope-equations into Slope-
Intercept FormIntercept Form
4 Examples 4 Examples
Converting linear Converting linear equations into Slope-equations into Slope-
Intercept FormIntercept Form
4 Examples 4 Examples
Slope intercept form is:
y = mx + b
Our main goal is to get the y alone on one side of the
equation
Example 1 - convert into slope-intercept Example 1 - convert into slope-intercept formform
Example 1 - convert into slope-intercept Example 1 - convert into slope-intercept formform
2 4 2y x 2 2 2
(divide both sides by 2 to get y alone)
(now simplify all fractions)
2 1
2 1y x
Slope (m) = 2
y-intercept (b) = 1
(divide both sides by 5 to get y alone)
(now simplify all fractions)
y = 2x + 3 BRAVO!!
Slope (m) = 2
y-intercept (b) = 3
5y = 10x + 15
*** Your turn – Example 2 – convert
into slope-intercept form ***
5 5 5
2 3
*** Your turn – Example 3 – convert
into slope-intercept form ***
-3y = -9x – 12Step 1: divide both sides by -3 to get y alone
Step 2: Simplify all fractions
Step 3: Write your equation in y = mx + b
Slope (m) =
y-intercept (b) =
*** Check Your Answer ***
(divide both sides by -3 to get y alone)
(now simplify all fractions)
y = 3x + 4
-3y = -9x – 12-3 -3 -3
Slope (m) = 3
y-intercept (b) = 4
21x – 7y = 14(subtract both sides by 21x)
-7y = -21x + 14 (divide both sides by -7)
y = 3x – 2(simplify all fractions)
Slope (m) = 3
y-intercept (b) = -2
Example 4 - convert into slope-intercept Example 4 - convert into slope-intercept formform
Example 4 - convert into slope-intercept Example 4 - convert into slope-intercept formform
-21x -21x
-7 -7 -7
3 2
2y + 26 = -6xStep 1: Subtract both sides by 26
Step 2: Divide both sides by 2 to get y by itself
Step 3: Simplify all fractions
***EXIT SLIP ***
Slope (m) =
y-intercept (b) =
2y + 26 = -6x(subtract both sides by 26)
2y = -6x – 26(now divide both sides by 2
y = -3x – 13
(simplify all fractions)
*** Check Your Answer ***
26 -26
2 2 2
Slope (m) = -3
y-intercept (b) = -13