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## #1 2013-10-25 03:31:59

lisathedork
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### Graphing Systems of Linear Equations

How do I graph these?

1. y = (2/3)x - 1
y = -x + 4

2. x + y = 0
3x + y = -4

3. 4x + 3y = -15
y = x + 2

4. x + 2y = -4
4y = 3x + 12

5. y = 2x
x + y = 3

6. x = 3 - 3y
x + 3y = -6

7. y = -2x + 1
y = x - 5

8. y = (1/2)x - 3
y = (3/2)x - 1

## #2 2013-10-25 05:04:05

bobbym
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### Re: Graphing Systems of Linear Equations

Hi lisa;

Welcome to the forum.

You make a table of x, y values and plot the points on graph paper. Start with the first one:

1. y = (2/3)x - 1

Now just plot point (0,-1) and (1,-1/3) in blue.

y = -x + 4

Click on the drawing below. Now you try the second one.

Now just plot point (0,4) and (1,3) in red.

Uploaded Images

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #3 2013-10-25 06:57:54

lisathedork
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### Re: Graphing Systems of Linear Equations

Shouldn't it be like that?

2x - 3y = -2
2(0) - 3y = -2
-3y = -2
y = 2/3
(0, 2/3)
2x - 3(0) = -2
2x = -2
x = -1
(-1, 0)

4x + y = 8
4(0) + y = 8
y = 8
(0, 8)
4x + y = 8
4x + 0 = 8
4x = 8
x = 2
(2, 0)

these are just examples.

Cause I know I have to found the y = mx + b

Last edited by lisathedork (2013-10-25 07:00:25)

## #4 2013-10-25 07:28:55

bob bundy
Moderator

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### Re: Graphing Systems of Linear Equations

hi lisathedork

Welcome to the forum.

You certainly can put x=0 and get y;  and then y=0 and get x.

Any pair of points will be enough to draw the line.

Q5 y = 2x.

Here using zero will only get one point (0,0) so you'll have to choose another value as well.

eg x = 5 .... y = 2 times 5 = 10 .......(5,10)

You don't need to get them in the format y = mx + b for this

eg

Q5 again

x + y = 3  any two numbers that add to 3 will do so (0,3) (1,2) (2,1) (3,0) (4,-1) 5,-2) .............

Bob

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

## #5 2013-10-25 08:12:30

lisathedork
Novice

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### Re: Graphing Systems of Linear Equations

I totally understand now. Thanx.

## #6 2013-10-26 07:59:07

ShivamS
Super Member

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### Re: Graphing Systems of Linear Equations

#### bobbym wrote:

Hi lisa;

Welcome to the forum.
...

First time bobbym calls someone by a shortened name!
Welcome Lisa.

I have discovered a truly marvellous signature, which this margin is too narrow to contain. -Fermat
Give me a lever long enough and a fulcrum on which to place it, and I shall move the world. -Archimedes
Young man, in mathematics you don't understand things. You just get used to them. - Neumann

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