2017­2­14 equation from two points.notebook
February 14, 2017
Today is Tues
2/14
Do Now:
-Take out HW
-Take calculator
-Copy tonight's HW
-Writing Equations from slope and 2 points
-Test on Thursday 2/23
Extra help 2/23 @ 7:20 am
Warm Up: Find the equation of the line
represented in the tables.
x
y
-2
-3
0
0
2
3
4
6
x
y
2
6
3
4
4
2
5
0
2017­2­14 equation from two points.notebook
February 14, 2017
HW Answers
x
-1
0
1
2
y
32
20
8
-4
m=
m=
x
0
2
4
6
y
5
10
15
20
Equation:
b=
x
y
-8
0
x
y
1
3
b=
-6
4
-4
8
-2
12
Equation:
b=
m=
m=
Equation:
b=
2
8
3
13
Equation:
4
18
2017­2­14 equation from two points.notebook
February 14, 2017
Today's Objective:
-Finding the equation of a line given the
slope and a point
-Finding the equation of a line given two
points
If you want to write an equation in
slope-intercept form:
y = mx + b
Use m and b.
If you do not know these values,
find them!
2017­2­14 equation from two points.notebook
February 14, 2017
Given: Slope and a Point
Find: Equation of the Line
1) Write the formula for slope­ intercept form of an equation.
y = mx + b
2) Plug in the slope. 3) Use the given point to plug in x and y values.
4) Solve for b.
5) Rewrite the equation using m and b.
Given: Slope and a Point
Find: Equation of the Line
Write an equation of the line that passes
through the point (-1,3) and has a slope of -4.
2017­2­14 equation from two points.notebook
Given: m = 7, point on line (1, -1)
Find: Equation of the Line
February 14, 2017
2017­2­14 equation from two points.notebook
February 14, 2017
Practice!!!! Find the equation of the line containing the given slope and point. m = 3 and (0, 10)
m = ­2 and (­5, ­2)
y = _x + _
y = _x + _
Given: Two Points
Find: Equation of the Line
1) Use the slope formula to find m
y2 - y1
m= x -x
2
1
2) Plug in the slope into y=mx+b. 3) Choose one of the points and plug in values for x and y into y=mx+b.
4) Solve for b.
5) Rewrite the equation using m and b.
2017­2­14 equation from two points.notebook
February 14, 2017
Write the equation of the line that passes
through the points (1,7) and (9,31).
What is the equation of a line that passes
through the points (-2,1) and (3, -9)?
2017­2­14 equation from two points.notebook
February 14, 2017
Practice!!!! Find the equation of the line containing the given points. (2, -15) and (-3, 5)
(4, 2) and (12, 4)
Ms. Mead has a super secret illuminati club. The club
charges a $25 flat fee to join. The club charges an
additional $10 for every month, m, that you are a
member. What equation represents the total cost, C, to
be in the club?
C = 10(m + 25)
C = 4m + 25
C = 10m + 25
C = 25m + 10
2017­2­14 equation from two points.notebook
February 14, 2017