Solving Equations by Graphing
Example #1:
Example #1:
First step is to set the equation equal to zero.
2x^2-x-6=0 (2x^2-x-6 is y1)
Next put the equation into your calculator with a standard window to look at it.
Make sure all stat-plots are turned off
2nd—Calculate—Zero
When you arrive at the graph to make your guess make sure the left bound is on the left side of the zero.
Right Bound is anywhere on the right side of the zero, and the guess should be on the x-axis 
After calculating the zero do the same thing for the left side of the parabola.
You should come out with x= -1.5 and y= 0
Example #2:
Left Side of the Equation= y1
Right Side of the Equation=y2
Enter the first part of the equation into y1 on your calculator and the second part into y2
To distinguish y1 from y2 on the graph go into the y= screen and all the way to the left of y2 hit enter to change to a thick line.
Next Go to 2nd—Calculate---Intersect---Enter---Enter
And then guess on one of the intersection points
Intersection points = (x= 2.30), (x= -2.50), (x= -1.24)
Solving Quadratic Equations
Learned Last Year:
1.) Factoring
2.) Quadratic Formula
3.) Completing the Square
4.) Extracting Square roots
5.) Graphing
We are going to talk about how each method works and when it is most effective to use each one.
Extracting Square Roots:
(2x-1)2=8
2x-1=±√8
2x=1 ± √8
x= (1 ±√8) / 2
x=(1 ± 2√2) / 2
x= ½ ± √2
Any time you have (__)2= # you will use extracting square roots
Homework:
Due 9/12/07
Pg. 142 #’s 28-38 Even
Due 9/14/07
Pg.155 #’s 1-10 Even
33-42 Even
43-52 Even
After calculating the zero do the same thing for the left side of the parabola.
You should come out with x= -1.5 and y= 0
Example #2:
Left Side of the Equation= y1
Right Side of the Equation=y2
Enter the first part of the equation into y1 on your calculator and the second part into y2
To distinguish y1 from y2 on the graph go into the y= screen and all the way to the left of y2 hit enter to change to a thick line.
Next Go to 2nd—Calculate---Intersect---Enter---Enter
And then guess on one of the intersection points
Intersection points = (x= 2.30), (x= -2.50), (x= -1.24)
Solving Quadratic Equations
Learned Last Year:
1.) Factoring
2.) Quadratic Formula
3.) Completing the Square
4.) Extracting Square roots
5.) Graphing
We are going to talk about how each method works and when it is most effective to use each one.
Extracting Square Roots:
(2x-1)2=8
2x-1=±√8
2x=1 ± √8
x= (1 ±√8) / 2
x=(1 ± 2√2) / 2
x= ½ ± √2
Any time you have (__)2= # you will use extracting square roots
Homework:
Due 9/12/07
Pg. 142 #’s 28-38 Even
Due 9/14/07
Pg.155 #’s 1-10 Even
33-42 Even
43-52 Even
8 comments:
I like the screen shots,
make sure you distinguish between multiplying by 2 and squaring something
yeah, pretty sweet screen shots. good job.
-marissa
Nice job!
the graphs from class are a really good idea.
it will help someone understand who missed that day of class
I also like the graphs and how it is very organized. It makes it easy to follow.
I like how easy it is to read and understand everything taht you included. The calculator images are really good and very helpfull.
see jenna you were the only one that was hatin on my post. its stellar and you know it. i think your just jelous that its better than yours.
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