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We start by finding three points that are solutions to the equation. We can choose any value for x or y , and then solve for the other variable.

Since y is isolated on the left side of the equation, it is easier to choose values for x . We will use 0 , 1 , and -2 for x for this example. We substitute each value of x into the equation and solve for y .

The figure shows three algebraic substitutions into an equation. The first substitution is for x = -2, with -2 shown in blue. The next line is y = 2 x + 1. The next line is y = 2 open parentheses -2, shown in blue, closed parentheses, + 1. The next line is y = - 4 + 1. The next line is y = -3. The last line is “ordered pair -2, -3”. The second  substitution is for x = 0, with 0 shown in blue. The next line is y = 2 x + 1. The next line is y = 2 open parentheses 0, shown in blue, closed parentheses, + 1. The next line is y = 0 + 1. The next line is y = 1. The last line is “ordered pair 0, 2”. The third substitution is for x = 1, with 1 shown in blue. The next line is y = 2 x + 1. The next line is y = 2 open parentheses 1, shown in blue, closed parentheses, + 1. The next line is y = 2 + 1. The next line is y = 3. The last line is “ordered pair -1, 3”.

We can organize the solutions in a table. See [link] .

y = 2 x + 1
x y ( x , y )
0 1 ( 0 , 1 )
1 3 ( 1 , 3 )
−2 −3 ( −2 , −3 )

Now we plot the points on a rectangular coordinate system. Check that the points line up. If they did not line up, it would mean we made a mistake and should double-check all our work. See [link] .

The graph shows the x y-coordinate plane. The x and y-axis each run from -7 to 7. Three labeled points are shown, “ordered pair -2, -3”, “ordered pair 0, 1”, and ordered pair 1, 3”.

Draw the line through the three points. Extend the line to fill the grid and put arrows on both ends of the line. The line is the graph of y = 2 x + 1 .

The graph shows the x y-coordinate plane. The x and y-axis each run from -7 to 7. A line passes through three labeled points, “ordered pair -2, -3”, “ordered pair 0, 1”, and ordered pair 1, 3”.

Graph a linear equation by plotting points.

  1. Find three points whose coordinates are solutions to the equation. Organize them in a table.
  2. Plot the points on a rectangular coordinate system. Check that the points line up. If they do not, carefully check your work.
  3. Draw the line through the points. Extend the line to fill the grid and put arrows on both ends of the line.

It is true that it only takes two points to determine a line, but it is a good habit to use three points. If you plot only two points and one of them is incorrect, you can still draw a line but it will not represent the solutions to the equation. It will be the wrong line. If you use three points, and one is incorrect, the points will not line up. This tells you something is wrong and you need to check your work. See [link] .

There are two figures. Figure a shows three points that are all contained on a straight line. There is a line with arrows that passed through the three points. Figure b shows 3 points that are not all arranged in a straight line.
Look at the difference between (a) and (b). All three points in (a) line up so we can draw one line through them. The three points in (b) do not line up. We cannot draw a single straight line through all three points.

Graph the equation y = −3 x .

Solution

Find three points that are solutions to the equation. It’s easier to choose values for x , and solve for y . Do you see why?

The figure shows three algebraic substitutions into an equation. The first substitution is for x = 0, with 0 shown in blue. The next line is y = -3 x. The next line is y = -3 open parentheses 0, shown in blue, closed parentheses. The next line is y = 0. The last line is “ordered pair 0, 0 “. The second substitution is for x = 1, with 0 shown in blue. The next line is y = -3 x. The next line is y = -3 open parentheses 1, shown in blue, closed parentheses. The next line is y = -3. The last line is “ordered pair 1, -3”. The third substitution is for x = -2, with -2 shown in blue. The next line is y = -3 x. The next line is y = -3 open parentheses -2, shown in blue, closed parentheses. The next line is y = 6. The last line is “ordered pair -2, 6 “.

List the points in a table.

y = −3 x
x y ( x , y )
0 0 ( 0 , 0 )
1 3 ( 1 , −3 )
−2 6 ( −2 , 6 )

Plot the points, check that they line up, and draw the line as shown.

The graph shows the x y-coordinate plane. The x and y-axis each run from -7 to 7. A line passes through three labeled points, “ordered pair -2, 6”, “ordered pair 0, 0”, and ordered pair 1, -3”. The line is labeled y = -3 x.
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Graph the equation by plotting points: y = −4 x .


The graph shows the x y-coordinate plane. The x and y-axis each run from -12 to 12. A line passes through the points “ordered pair 0, 0” and “ordered pair 4, -4”.

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Graph the equation by plotting points: y = x .


The graph shows the x y-coordinate plane. The x and y-axis each run from -12 to 12. A line passes through the points “ordered pair 0, 0” and “ordered pair 1, -4”.

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When an equation includes a fraction as the coefficient of x , we can substitute any numbers for x . But the math is easier if we make ‘good’ choices for the values of x . This way we will avoid fraction answers, which are hard to graph precisely.

Graph the equation y = 1 2 x + 3 .

Solution

Find three points that are solutions to the equation. Since this equation has the fraction 1 2 as a coefficient of x , we will choose values of x carefully. We will use zero as one choice and multiples of 2 for the other choices.

The figure shows three algebraic substitutions into an equation. The first substitution is for x = 0, with 0 shown in blue. The next line is y = 1 over 2 x + 3. The next line is y = 1 over 2 open parentheses 0, shown in blue, closed parentheses, + 3.  The next line is y = 3. The last line is “ordered pair 0, 3”. The second substitution is for x = 2, with 2 shown in blue. The next line is y = 1 over 2 x + 3. The next line is y = 1 over 2 open parentheses 2, shown in blue, closed parentheses, + 3.  The next line is y = 4. The last line is “ordered pair 2, 4”. The third substitution is for x = 4, with 4 shown in blue. The next line is y = 1 over 2 x + 3. The next line is y = 1 over 2 open parentheses 4, shown in blue, closed parentheses, + 3.  The next line is y = 5. The last line is “ordered pair 4, 5”.

The points are shown in the table.

y = 1 2 x + 3
x y ( x , y )
0 3 ( 0 , 3 )
2 4 ( 2 , 4 )
4 5 ( 4 , 5 )

Plot the points, check that they line up, and draw the line as shown.

The graph shows the x y-coordinate plane. The x and y-axis each run from -7 to 7. A line passes through three labeled points, “ordered pair 0, 3”, “ordered pair 2, 4”, and ordered pair 4, 5”. The line is labeled y = 1 over 2 x + 3.
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Graph the equation: y = 1 3 x 1 .


The graph shows the x y-coordinate plane. The x and y-axis each run from -12 to 12. A line passes through the points “ordered pair 0, -1” and “ordered pair 3, 0”.

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Graph the equation: y = 1 4 x + 2 .


The graph shows the x y-coordinate plane. The x and y-axis each run from -12 to 12. A line passes through the points “ordered pair 0, 2” and “ordered pair -12, 0”.

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So far, all the equations we graphed had y given in terms of x . Now we’ll graph an equation with x and y on the same side.

Graph the equation x + y = 5 .

Solution

Find three points that are solutions to the equation. Remember, you can start with any value of x or y .

The figure shows three algebraic substitutions into an equation. The first substitution is for x = 0, with 0 shown in blue. The next line is x + y = 5. The next line is 0, shown in blue + y = 5. The next line is y = 5. The last line is “ordered pair 0, 5”. The second substitution is for x = 1, with 1 shown in blue. The next line is x + y = 5. The next line is 1, shown in blue + y = 5. The next line is y = 4. The last line is “ordered pair 1, 4”. The third substitution is for x = 4, with 4 shown in blue. The next line is x + y = 5. The next line is 4, shown in blue + y = 5. The next line is y = 1. The last line is “ordered pair 4, 1”.

We list the points in a table.

x + y = 5
x y ( x , y )
0 5 ( 0 , 5 )
1 4 ( 1 , 4 )
4 1 ( 4 , 1 )

Then plot the points, check that they line up, and draw the line.

The graph shows the x y-coordinate plane. The x and y-axis each run from -7 to 7. A line passes through three labeled points, “ordered pair 0, 5”, “ordered pair 1, 4”, and ordered pair 4, 1”. The line is labeled x + y = 5.
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Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
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Maciej
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s. Reply
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Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
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s. Reply
of graphene you mean?
Ebrahim
or in general
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in general
s.
Graphene has a hexagonal structure
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what's the easiest and fastest way to the synthesize AgNP?
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Cied
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abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
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I'm interested in nanotube
Uday
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what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
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after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
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name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
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silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
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Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
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Practice Key Terms 2

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Source:  OpenStax, Prealgebra. OpenStax CNX. Jul 15, 2016 Download for free at http://legacy.cnx.org/content/col11756/1.9
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