Vector Form: Line Passing Through (2, -1) and Parallel to 2x-3y=1

In summary, the conversation discusses finding the vector form of a line in the plane that passes through a given point and is parallel to another line. The solution involves using the slope of the given line to determine the slope of the parallel line, and then using this slope to find the vector form of the line. The conversation also touches on the importance of checking one's work and understanding the concepts involved.
  • #1
Math9999

Homework Statement


Find the vector form of the equation of the line in ℝ2 that passes through P=(2, -1) and is parallel to the line with general equation 2x-3y=1.

Homework Equations


None.

The Attempt at a Solution


vector form: x=p+td
general form: ax+by=c
--------------------------------
a=2, b=-3, so [x, y]=[2, -1]+t[2, -3], am I right?
 
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  • #2
Math9999 said:

Homework Statement


Find the vector form of the equation of the line in ℝ2 that passes through P=(2, -1) and is parallel to the line with general equation 2x-3y=1.

Homework Equations


None.

The Attempt at a Solution


vector form: x=p+td
general form: ax+by=c
--------------------------------
a=2, b=-3, so [x, y]=[2, -1]+t[2, -3], am I right?

That looks like a guess. Can you draw those two lines and see whether they are parallel or not?
 
  • #3
They are but how do I figure out the normal vector?
 
  • #4
Math9999 said:
They are but how do I figure out the normal vector?

They are not parallel.
 
  • #5
So I thought that the normal vector should be 2 and -3 based on the general form on the problem but now I don't think that's true. So how do I figure out the normal vector?
 
  • #6
Math9999 said:
a=2, b=-3, so [x, y]=[2, -1]+t[2, -3], am I right?
You can (and should) check this yourself. Clearly, the line from your equation goes through the point (2, -1). Do you see why? But does it have the right slope?
PeroK is saying that the line you calculated and the given line aren't parallel, which should suggest to you that your slope isn't right.

As a check on your work, find the equation of the line you're after, using the point-slope form of the equation of the line. That line should agree with the one you've calculated using a vector form.

Math9999 said:
So how do I figure out the normal vector?
Why do you need the normal vector?
 
  • #7
So 2x-3y=1, 3y=2x-1, y=2/3x-1/3 and m=2/3, which is the slope?
 
  • #8
Math9999 said:
So 2x-3y=1, 3y=2x-1, y=2/3x-1/3 and m=2/3, which is the slope?
Yes, that's the right slope. Now you should be able to get the equation in vector form.
 
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  • #9
But how? I still don't get it. If the right slope is m=2/3, then how is the answer [x, y]=[2, -1]+t[3, 2]?
 
  • #10
Math9999 said:
But how? I still don't get it. If the right slope is m=2/3, then how is the answer [x, y]=[2, -1]+t[3, 2]?
What's the slope of the vector <3, 2>? Try drawing it in the plane.
 
  • #11
m=rise/run=2/3?
 
  • #12
Math9999 said:
m=rise/run=2/3?
Yes
From post #1
Math9999 said:
Find the vector form of the equation of the line in ℝ2 that passes through P=(2, -1) and is parallel to the line with general equation 2x-3y=1.
Post #9
Math9999 said:
If the right slope is m=2/3, then how is the answer [x, y]=[2, -1]+t[3, 2]?
Is there some value of t for which <x, y> = <2, -1>? IOW, does the line pass through (2, -1)?
Is the line represented by your vector equation parallel to the line whose equation is 2x - 3y = 1?
.
 
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1. What is a vector form?

A vector form is a way of representing a line or a plane in a coordinate system using a vector equation. It is often used in mathematics and physics to describe the motion of objects in a given space.

2. How do you find the vector form of a line?

To find the vector form of a line, you need to know a point on the line and a vector that is parallel to the line. The vector form is written as r = a + tb, where r is a position vector, a is a point on the line, and b is the direction vector.

3. What does it mean for a line to be parallel to another line?

Two lines are parallel if they have the same slope and will never intersect. This means that they will have the same direction vector and will be a certain distance apart from each other.

4. How do you determine if a line is parallel to 2x-3y=1?

A line is parallel to 2x-3y=1 if its slope is equal to the slope of the given line. To find the slope of a line, we use the formula y = mx + b, where m is the slope. In this case, the slope is 2/3. Therefore, any line with a slope of 2/3 will be parallel to 2x-3y=1.

5. What is the equation of the line passing through (2, -1) and parallel to 2x-3y=1?

The equation of the line passing through (2, -1) and parallel to 2x-3y=1 can be found using the point-slope form. We know the slope is 2/3 and the point (2, -1) is on the line. Therefore, the equation is y - (-1) = 2/3(x - 2), which simplifies to y = 2/3x - 5/3.

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