Linear Equations; graphing linear equation

[cluelessboutmath]

Hey..i made a c on my last test bc of linear equations and graphing them...for the one i made the most mistakes on, the directions were: Write a linear equation in function form from the following lines on the graph..i don't really get this

 

[Denis]

If you want help, post the problem IN FULL.

 

[jermaine]

graph each equation plot at least five points for each equation. Use graph paper


x-2y=6

 

[Deleted member 4993]

graph each equation plot at least five points for each equation. Use graph paper


x-2y=6

For a quick review with examples, go to:

http://www.purplemath.com/modules/graphlin.htm

 

[Aladdin]

graph each equation plot at least five points for each equation. Use graph paper


x-2y=6---> Is this an example ?

And why to take 5 points ? -- It's a linear equation right ?? OR a function ??

 

[stapel]

And why to take 5 points ? -- It's a linear equation right ?? OR a function ??

It is a linear equation in two variables, which makes it a linear function.

The student should "take 5 points" because the instructions specified that the student should. :roll:

 

[Aladdin]

Re:

And why to take 5 points ? -- It's a linear equation right ?? OR a function ??

It is a linear equation in two variables, which makes it a linear function.

The student should "take 5 points" because the instructions specified that the student should. :roll:

Why 5 points ?? , two points are sufficient .. correct ?

 

[Mrspi]

While it is true that two points are sufficient to determine a line, in elementary algebra, students are often requested to find MORE than two points....Why??? Because if one or both of the TWO points you plot is incorrect, and you draw the line through those two points, you'll have a line all right, but it won't be the CORRECT line. By plotting more points, an error in calculation is easier to spot. If you've found three points for a linear equation, and they DON'T all lie on the same line, you know that one or more of your calculations is erroneous.

Finding the coordinates for more than two points also gives the student practice in substituting a value for one of the variables, and solving for the other.

AND...if the equation is non-linear, it will necessarily take more than two points to sketch an accurate graph.

 

[Aladdin]

Finding the coordinates for more than two points also gives the student practice in substituting a value for one of the variables, and solving for the other.

AND...if the equation is non-linear, it will necessarily take more than two points to sketch an accurate graph.

Okay, I agree but wont that take time from the test. Yes it sure help students substituting but my point is :
Must the student plot these 5 points in the test ,knowing that, this student had been practicing this at home.

Yes, sure if it's non-linear, sure he must take more than 2 points.

 

[Deleted member 4993]

Looking at the original post - you should be able to tell that the student has not grasped the idea of substitution very well (or was sleeping in the class). So calculating coordinates of 5 points will serve the student well.

Teachers do not assign home-work problem to minimize the amount of time - they assign it to teach certain idea. Repeatation is essential at the begining to root the idea well.

Do not diregard the point of checking your calculation by looking at the graph - I almost always plot three-points for a straight-line, when I do it without a spreadsheet.

 

[Aladdin]

Looking at the original post - you should be able to tell that the student has not grasped the idea of substitution very well (or was sleeping in the class). So calculating coordinates of 5 points will serve the student well.

Teachers do not assign home-work problem to minimize the amount of time - they assign it to teach certain idea. Repeatation is essential at the begining to root the idea well.

Do not diregard the point of checking your calculation by looking at the graph - I almost always plot three-points for a straight-line, when I do it without a spreadsheet.

Well, thats convencing I totally agreed with what you said.
Thank you.