Tuesday, November 27, 2007

How do you graph using the slope-intercept method?

Pretend that you are teaching someone to graph a line using the slope-intercept method (that is what we have been doing in class). What would you tell them? Try to explain the process so that anyone could do it.

Use the equation: x - 2y = 6

21 comments:

waltnich said...

Do the know how to do algebra first

b-guillen said...

2x+3y=6
3y=-2x+6
divide -2 and 6 by 3
y=-2/3+2
slope=-2/3
y point=(0,2)
and then you start in a graph at positive 2 then you go down 2 and over three.

Shannon said...

The first thing I'd tell them is to solve for y (and assume they know how to do this). . After they arrive at the answer of y=-1/2x+3, I would explain to them that 3 is actually (0,3), which is where the line they are graphing crosses the y axis. From there, I would tell them that -1/2 is rise over run, so they would need to go down one (hence the negative sign), and over two, and repeat those same movements until they form a line. First, though, I would explain to them how to figure out if a slope is steep, flat, or neutral, if it crosses below or above the x axis, and if the line goes up or down.

Tricia Michiels said...

The first thing I would tell them is to islate y. The way to this would be (with the problem written): x-2y=6
x+-x+-2y=6+-x
-2y=-x+6
-2/-2=-x/-2+6/-2
y=1/2x+-3
After they have solved for y, they should determine the slope and the slope intercept. The way to identify slope is m=x and the way to identify slope intercept is b=(0,b) This would be shown as: m=1/2
b=(0,-3)
The last thing would be to graph them. The way to graph is put a point at (0,-3) on the graph. Knowing that the slope is positive, the graph will go up so, they should go up one and to the right two and continue. Then to put the points below, but still keep the slope positive, they should go down one and to the left two. Then they just have to draw a line through the dots.
That is how to graph an equation.

Megan said...

I would first tell them that they are trying to isolate the Y variable. I would write it as...
X-2y=6
Then change it to addition...
X+-2y=6
Then switch the x to the other side, making it it's opposite, -X.
-2y= -X + 6
Then divide both sides by the y value, -2.
-2y/-2= -X/-2 + 6/-2
To get..
y=1/2X + -3

After they have solved the problem, I would tell them that the 1/2 is actually the slope, and -3 is the y-intercept. I would explain that -3 is really (0,-3) and tell them to start on the graph at the point (0,-3) and from there to go up 1 point and over 2 to the right. I would then tell them to continue this pattern until they have enough dots to make a line. I would tell them to connect the dots, making a line, and put arrows on the end to symbolize that the line continues on.

Tinkerbell said...

The first thing that i would tell them would be to add the opposite to each side:
-2x+2x+3y=6+-2x
3y=6+-2x
Then i would tell them to divide by three on each side so that the equation reads y=
3y/3=6+-2x/3
y=-2/3x+2
Then i would tell them that the slope is the x, or number before it, and the intercept is the second number. Which means where it crosses on the y axis.
m=-2/3
y-intercept (0,2)

Gaven Brault said...

first i would write the problem down
x-2y=6
then i would add -x to both sides like this
x+-x-2y=6+-x
then the problem would be -2y=6+-x
next i would say divide both sides by a -2
like this
-2y=6+-x
________
-2 -2

which would then give you y=-3+1/2x

then you should move the 1/2x and -3 around
like this

y=1/2x+-3

and thats how i would teach someone to do this problem!!!

TiredTeenager said...

The problem is x-2y=6
First I would have them add a negative x. Then they would have
-2y=-x+6
Then you would divide by -2. You would then get y=1/2+-3

1/2 is the slope. 1 is the rise and 2 is the run. (0,-3) is the y-intercept point. You would then start graphing at the -3. Then you would go up 1 and over 2. That spot would be you need point.

Amber D.

Danielle v. said...
This comment has been removed by the author.
Danielle v. said...
This comment has been removed by the author.
Danielle v. said...

x-2y=6
first you have to get x to the other side, so you add a -x to each side
-2y=-x+6
Now you have to get y alone, so you divide by -2. Now you have:
y=1/2x+-3
The slope would be 1/2
1 is the rise and 2 is the run. The y intercept is -3, which is the point (0,-3).
You start at the point (0,-3). Then you would go up 1 and over 2.

reynolds said...

x - 2y = 6
(assuming that they know how to do algebra) solve for "y"
ADD NEGATIVE "x" TO BOTH SIDES
-x+x-2y=6+-x
DIVIDE BOTH SIDES BY COEFFICIENT OF "y"
-2y=6+x
-2 -2
y=(-3)+1/2x

sam said...

First you try to get "y" by itself
- next you want to move the 2x to the other side of the equal sign.
- when you move the 2x it becomes a negative number.
-since the equation should look like 3y=`2+6. then you would divide 3y to `2 and 6
- Your equation now looks like y=`2/3+2
- the y intersept point is (0,2)
- and the slope is 2/3
- next you go to (0,2) on the graph and plot a point there, then you go up do lines and over three lines
- the reason why this is becuase if you keep repeating the pattern you eventually have a line
- and that is how you graph 2x=3y=6


Sam H.

Ben said...

first solve the equation for Y. You'll get Y=1/2x+-3. The slope is 1/2 and the Y value is -3. This means that on the graph, you start out at -3 on the Y axis. Then you go up one over 2 and mark the point each time. Connect the dots and your done.

evan said...

when it gives you an equation first you must solve for y. Then once you do that you mark your y point. Then you and see which number of the slop is on top then u go up or down depending if it is negative or positive, then for the number on the bottom (if it is a whole number it would be one) you go that many to the right.

evan said...

when it gives you an equation first you must solve for y. Then once you do that you mark your y point. Then you and see which number of the slop is on top then u go up or down depending if it is negative or positive, then for the number on the bottom (if it is a whole number it would be one) you go that many to the right.

levi budz said...

the first thing i say is u solve for y and then u solve for x. then u figure out the promble so y=mx+b. then u plug the number in to the graph. you keep ploting your points then u connect the dots and u r finshed

Bryan said...

You would first have to get the 2x and the six on the same side. You do that by subtracting it from the left side and adding it to the other side (2x-2x+3y=6+-2x). Then you get the y by itself by dividing by three on each side (3y/3=6/3+(-2x)/3). The answer then equals y=-2/3x+2. The second number is the y intercept point so put a point at 2. The slope is -2/3 so go down 2 from the first point and over to the right 3 and put another point. Then draw the line to make the graph.

k8storm said...

-2y=-x+6
divide by -2 to both sides
y=-1/2x+3
the slope is -1/2 y point(0,3)
then you're done =]

erin said...

First you start with your problem
2x+3y=6 and you goal would be to get the y all by itself. To do this you would add a -2x to the 2x and to the 6.
2x+-2x+3y=6+-2x
The 2x and -2x would cancel out.
3y=6+-2x
Then to get the y by itself you would divide 3y with 3 and 6+-2x with 3. You then would have
y=1/2x+3
To graph this the slope would be 1/2 and the y point would be
(0,2). You would go to the 2 on the y axis and go up one and 2 to the right.

Maes said...

I would start out by writing down the problem x-2y=6. Then I would add a negative x to both sides making the problem 2y=-x+6. THen I would divide both sides by 2 making the new problem y=-1/2x+3.
The slope is -1/2. The Starting point is (0,3). You would then go down 1, then over 2, down 1 then over 2. The line would be going down, be flat and crosses y above the x axis.