Download Unit 3, Lesson 5

EQUATIONS IN TWO
VARIABLES
Unit 3, Lesson 5
November 19th, 2014
February 17, 2015
DO NOW (3 MINS)
PRIOR KNOWLEDGE BOX (PKB)
Topic: Equations in two variable
Write about what you know
about the topic above.
Misconceptions
STANDARDS
A-CED.2: Create equations that describe numbers or relationships.
•
Create equations and inequalities in two or more variables to represent
relationships between quantities; graph equations on coordinate axes
with labels and scales.
A-REI.10 Represent and solve equations and inequalities graphically.
•
Understand that the graph of an equation in two variables is the set of all
its solutions plotted in the coordinate plane, often forming a curve (which
could be a line).
OBJECTIVE
•
•
Huskies will be able to
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define the solutions of a linear equation in two variables
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Use various techniques to graph a linear equation in two variables
•
Find the solutions to a linear equation in two variables using
substitution and graphing
Huskies will show success of the criteria above by earning a 3 out of
4 on the exit slip today
VOCABULARY
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Standard Form- An equation of a line that has the
following formula Ax + By = C, where A≠0 and
B≠0.
Examples of Standard Form
Equations
Non-Examples
3x + 5y = 3
2y = 4x + 2
2x - y = 6
x=6-y
-2x + y = 7
y = 2x + 7
LINEAR EQUATIONS IN
TWO VARIABLES
Identify the equations that are not linear equations in
two variables, and explain why.
Equation
x+y=1
y=3
2x2 + y =25
x + y = 2x +y -1
m+n=1
x+y=z
1
y= x+2
2
1 1
+ =0
x y
THE GRAPH OF LINEAR
EQUATIONS
The graph of a linear equation in two variables
line. To be a linear equation it must be a first degree equation.
Discuss:
x + 2y = 7
What different methods could you use to graph this equation?
How would you determine where the line intersected the xand y-axes?
FINDING SOLUTIONS
Given a value for one of the variables, you can find a solution
to the equation by solving for the other variable.
1. What is the solution to the equation 2x + y = 9 when x = 0.5?
2. What is the solution to the equation 2x +y = 9 when y = 0.5
3. Find three more solutions to the equation 2x +y = 9
Graph the equation. Find the x-intercept. Find the y-intercept. What is the
slope of the line?
Graph 2y - x = 7
Graph y = -2x - 3
Graph 2x + y = 9
1. Describe each line
What is the slope of 2x + y = 9
& 2y - x = 7
What can we say about the
slope of parallel and
perpendicular lines?
YOU TRY
For each of the following equations, determine where the
graph intersects the x- and y-axes and then create a graph.
a. 2x = y +4
b. y =1 -x
c. 2x+2y +5 = 0
YOU TRY 1
x-intercept:
y-intercept:
Graph 2x = y +4
Don’t forget: x-intercept (x, 0)
y-intercept (0,y)
YOU TRY 2
x-intercept:
y-intercept:
Graph y = 1 - x
Don’t forget: x-intercept (x, 0)
y-intercept (0,y)
YOU TRY 3
x-intercept:
y-intercept:
Graph 2x + 2y +5=0
Don’t forget: x-intercept (x, 0)
y-intercept (0,y)
LINEAR EQUATIONS IN TWO
VARIABLES
Read and Discuss the handout (elbow partners).
Refer to the the different graphs above
GUIDED PRACTICE
PAGE 9
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Dos Variable Equations Cafe Menu
Make sure that you fill your knowledge tank up by
completing as much as you can!
•
Appetizers
•
Entree
•
Desert
you complete the challenge
Your reward today = working towards a stamp!!
PRIOR KNOWLEDGE BOX (PKB)
Topic: Equations in two variable
Misconceptions
What did you think you knew
but you found out was a
misconception? If you didn’t
have any prior knowledge,
what did you learn/review
today?