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Write an equation of a line with undefined slope that passes through the point(3,-2)

 
BOSEOK  Sep 17, 2017
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10+0 Answers

 #1
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0

y=-2. 

Because the line is horizontal, the slope is undefined. 

 
Gh0sty15  Sep 17, 2017
 #2
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How can I know that line is horizontal?

 
BOSEOK  Sep 17, 2017
 #3
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+1

The slope of a horizontal line is well defined- it is zero.

 

I think what is wanted is as follows:

 

General equation of a straight line is y =mx + c

 

Here we know that this line goes through point (3, -2) so we can say

-2 = m*3 + c

 

This means c = -2 - 3m.  Put this in the equation for the line:

 

y = mx - 2 - 3m

 

or

 

y = m(x - 3) - 2

 

The slope m is undefined.

 
Alan  Sep 17, 2017
 #4
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But my answeris x=3.

 
BOSEOK  Sep 17, 2017
 #7
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Ok. x = 3 is a vertical line.  This has infinite slope, so is basically undefined.

 

(I repeat: a horizontal line has zero slope).

 
Alan  Sep 17, 2017
 #5
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To put it simply, in linear equations, if an equation is y= (any real number), then it is horizontal. For example, y=2 is horizontal, and it has an undefined slope. x=3 is actually a vertical line. Its slope is 0.

 

Correct me if I'm wrong. laugh

 
Gh0sty15  Sep 17, 2017
 #6
avatar+1088 
+1

BOSEOK is correct; the equation is x=3.

 

Contrary to what Gh0sty stated, the slope is defined when a linear function happens to be horizontal. Let's figure out the slope of the graph provided by Gh0sty. I will use the points \((3,-2)\) and \((0,-2)\). Let's find the slope.

 

Of course, the formula for slope is the following:

 

\(m=\frac{y_2-y_1}{x_2-x_1}\)

 

\(m=\frac{-2-(-2)}{0-3}\) Continue to simplify the fraction.
\(m=\frac{0}{-3}=0\)  
   

 

The slope is 0. 0 is a valid number for the slope. If you type into Demos y=0x-2, the line will appear exactly as the picture above. 

 

Let's try calculating the slope of the line x=-3. Two arbitrary points on the line are \((-3,2)\) and \((-3,0)\)

 

What is the slope of this? Let's try using the formula again. Let's see what happens.

 

\(\frac{0-2}{-3-(-3)}\) Simplify both the numerator and the denominator.
\(\frac{-2}{0}\)  
   

 

Of course, any number divided by 0 is undefined and therefore it has an undefined slope. 

 

Therefore, BOSEOK's answer is correct because it meets both criteria of

 

1) A line with an undefined slope

2) A line that passes through the point \((3,-2)\)

 

And therefore, \(x=3\) is correct. 

 
TheXSquaredFactor  Sep 17, 2017
 #8
avatar+351 
0

Hey...I was wrong. (Again.)

Sorry Boseok.

 
Gh0sty15  Sep 17, 2017
 #9
avatar+351 
0

Sorry Alan.

 
Gh0sty15  Sep 17, 2017
 #10
avatar+26094 
+1

No problem! Don't worry about it.

 
Alan  Sep 17, 2017

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