Transcript 3-2 Solving Linear Equations by Graphing

3-2 Solving Linear Equations by
Graphing
Before we begin A short review
http://www.youtube.com/watch?v=YPWlAY3y3_g
https://www.youtube.com/watch?v=mxBoni8N70Y
Free graphing calculators for phones
Essential Question:
I-phone
https://itunes.apple.com/us/app/freegraphing-calculator/id378009553?mt=8
Android
https://play.google.com/store/apps/details?i
d=com.algeo.algeo&hl=en
Why are graphs useful?
http://www.regentsprep.org/regents/math/
algebra/ac1/eqlines2.htm
Activities for today:
Warm-up
Review HW
New Lesson: Solving Linear Equations by
Graphing
If time: work on homework and/or project
I will be able to….
•Solve linear equations by graphing
•Estimate solutions to a linear equation by
graphing
A short review
Determine whether y= -2x -9 is a linear
equation.
Determine whether 3x – xy + 7 = 0 is a linear
equation. If it is, write the equation in
standard form.
Graph y = -3x + 3
Jake’s Windows used the equation c= 5w + 15.25 to
calculation the total charge c based on the number of
windows w that are washed. What will be the charge for
washing 15 windows?
A short review/ Let’s begin the lesson
Which linear equation is represented by this
graph?
A.
y=x–3
B.
y = 2x + 1
C.
y=x+3
D.
y = 2x – 3
New vocabulary:
•Linear function
•Parent function
•Family of graphs
•Root
•Zeros
Solve an Equation with One Root
Solve algebraically : 0 = ½ x + 3
Some more examples
Solve by graphing
1
2= x+3
3
Solve algebraically
2
-2 = 3 x + 4
Some more examples
3
Solve by graphing 6 = - 4 x + 9
Solve 2x + 5 = 2x + 3 algebraically.
Some examples
Solve 5x -7 = 5x + 2 graphically
Solve -3x + 6 = 7 – 3x algebraically
Some more examples
Solve 4- 6x = -6x + 3 by graphing
Recap: An equation can be solved by
graphing or algebraically.
A linear equation can have one root, all real
numbers or no answers.
Real World Examples
Kendra’s calss is selling greeting
cards to raise money for new soccer
equipment. They paid $115 for the cards,
and they are selling each card for $1.75.
thefunction y = 1.75x – 115 represents their
profit y for selling x greeting cards. Find the
zero of the this value means in this context.
Make a table and graph.
x
x
(x,y)
Real World Examples
On a trip to his friend’s house, Raphael’s
average speed was 45 miles per hour. The
distance that Raphael is from his friend’s
house at a certain moment in the trip can be
represented by d = 150 – 45t, where d
repesents the distance in miles and t is the
time in hours. Find the zero of the this value
means in this context.
Make a table and graph.
x
x
(x,y)