review of slope and the slope intercept formula
TRANSCRIPT
Review of Slope and the slope intercept formula
y=mx+b
change in ym slope
change in x
What is the slope of the line that contains these points?
Point A (0,3)
Point B (2,2)
+2
+3 A
Brise
sloperun
The slope of this line is..
+2
+3 A
B
3
2slope
riseslope
run
What is the slope of this line?
-2
+2
riseslope
run
What is the slope of this line?
-2
+2
2
2slope
21
2
What is the slope of this line?
+2
+1
riseslope
run
What is the y -intercept of this line?
• In other words, at what coordinate does the line cross the y-axis?
• y intercept is -5
y axis
x axis
What is the y -intercept of this line?
• At what coordinate does the line cross the y-axis?
• y intercept is 0
y axis
x axis
What is the y -intercept of this line?
• At what coordinate does the line cross the y-axis?
• y intercept is +5
y axis
x axis
What is the y -intercept of this line?
• At what coordinate does the line cross the y-axis?
• y intercept is -2
y axis
x axis
How to write the equation
for this line -2
+221
2m
y mx b
5b
1 5y x
Write an equation for this line.
+2
+3
3
2slope
1b
31
2y x
y mx b
What is the slope of this line?
+2
+1
1
2slope
0b
10
2y x 1
2y x
y mx b
Write an equation for this line.
y axis
x axis1
55
y x
Write an equation for this line.
y axis
x axis2
25
y x
What is the slope of this line?
0slope
2y
What is the slope of this line?
slope undefined
4x
Review Part Two
Finding Slope without Graphing
When you are given two points you may have to find the slope...
Point A (2,-3)
Point B (3,4)
…without graphing.
A B
change in yslope
change in x
Find the slope when you are given two points from a line.
Point A (2,-3)
Point B (3,4)
Use the formula for slope.
Remember, m=slope.
2 1
2 1
y ym
x x
Find the slope when you are given two points from a line.
Point 1 (2,-3)
Point 2 (3,4)
Use the formula for slope.
Remember, m=slope.
2 1
2 1
y ym
x x
4 3
3 2m
77
1m
Using the same points, but labeling them #2 and #1
Point 2 (2,-3)
Point 1 (3,4)
Use the formula for slope.
Remember, m=slope.
2 1
2 1
y ym
x x
3 4
2 3m
77
1m
Find the slope when you are given the following two points from a line.
Point C (-2,-6)
Point D (3,5)
Use the formula for slope.
Remember, m=slope.
2 1
2 1
y ym
x x
5 6
3 2m
11
5m
Find the slope when you are given the following two points from a line.
Point E (9,6)
Point F (1,4)
Use the formula for slope.
Remember, m=slope.
2 1
2 1
y ym
x x
4 6
1 9m
2 1
8 4m
Review Part Three
Finding the equation from two given points from the line
Find the Linear Equation
Point E (9,6)
Point F (1,4)
You found the slope (m) to be ¼.
Insert ¼ as m in the slope intercept formula.
Let’s pick the x and y values from Point F and insert them into the formula. (1,4)
1
4y x b
14 (1)
4b
14
4b
334b
Write the Linear Equation
Point E (9,6)
Point F (1,4)Now use the value for
the slope (m) and y-intercept (b) to rewrite the formula.1
4 (1)4
b
14
4b
334b
1 33
4 4y x
Write the Linear EquationUse points R and S
Point R (5,3)
Point S (1,7)
Reminder: (x,y)
Substitute the values for Point R.
3 = -1(5) + b
3 = -5 + b
(Add 5 to both sides)
1y x b
8 b
7 3 4
1 5 4m
y mx b 1 8y x
8y x
Write the Linear EquationUse points W and T
Point W (-4,-3)
Point T (-2,-6)
Substituting the values for Point T…
-6 = -3/2(-2) + b
-6 = +6/2 + b
(Subtract 3 from both sides)
3
2y x b
9 b
6 3 3
2 4 2m
y mx b
39
2y x
Review Part Four
Find the x and y intercepts
Given: y = -3x + 12
• Use zero as the x value.y = -3(0) + 12
y = 12
Replace (x,y) with 0 and 12.
(0,12)
• Use zero as the y value.0 = -3x + 12Subtract 12 from both sides
- 12 = -3xDivide both sides by -3- 12 = -3x -3 -3
-4 =xReplace (x,y) with -4 and
0.(-4,0)
Given: y = -4x + 8Find the x and y intercepts.
• Use zero as the x value.
• Then use zero as the y value.
x y
0 ?
? 0 x intercept is (0,-8)y intercept is (2,0)
Assignment
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