Parallel, Perpendicular, or Neither

  • Thread starter nycmathguy
  • Start date
  • #1
Homework Statement:
Determine whether the lines are parallel,
perpendicular, or neither.
Relevant Equations:
Linear Equations
Determine whether the lines are parallel,
perpendicular, or neither.

Line 1: y = (x/4) − 1

Line 2: y = 4x + 7

Looking at the slopes of the lines, I say neither. Is (1/4) the negative reciprocal of 4?
I say no.

My answer is neither.
 

Answers and Replies

  • #2
Delta2
Homework Helper
Insights Author
Gold Member
5,695
2,473
You answer is correct but you provide half the justification. I guess you omit the other half (why they are not parallel) because it seems obvious to you.
 
  • #3
You answer is correct but you provide half the justification. I guess you omit the other half (why they are not parallel) because it seems obvious to you.

The lines are not parallel because their slope is not the same.
 
  • #4
berkeman
Mentor
64,441
15,791
Homework Statement:: Determine whether the lines are parallel,
perpendicular, or neither.
Relevant Equations:: Linear Equations

Determine whether the lines are parallel,
perpendicular, or neither.

Line 1: y = (x/4) − 1

Line 2: y = 4x + 7

Looking at the slopes of the lines, I say neither. Is (1/4) the negative reciprocal of 4?
I say no
.

My answer is neither.
The lines are not parallel because their slope is not the same.
I think @Mark44 has given you this tip before, but the "Relevant Equations" is a place where you should explicitly list the equations or methods that can be used to solve the problem, not for a general statement like "Linear Equations".

In this case, while solving the problem you did list the relevant concepts / conditions for parallel and perpendicular lines. Those should have been listed in the Relevant Equations section at the start, and then you can apply those conditions to the problem (finding the slopes and using the Relevant Equations/Conditions) to solve the problem. Does that make sense? :smile:
 
  • #5
I think @Mark44 has given you this tip before, but the "Relevant Equations" is a place where you should explicitly list the equations or methods that can be used to solve the problem, not for a general statement like "Linear Equations".

In this case, while solving the problem you did list the relevant concepts / conditions for parallel and perpendicular lines. Those should have been listed in the Relevant Equations section at the start, and then you can apply those conditions to the problem (finding the slopes and using the Relevant Equations/Conditions) to solve the problem. Does that make sense? :smile:

Not really. Can you give me another example of RELEVANT EQUATIONS?

Say the problem is solve y = mx + b for b.

1. What is the HW Statement?
2. What should the Relevant Equations be?
 
  • #6
berkeman
Mentor
64,441
15,791
Say the problem is solve y = mx + b for b.

1. What is the HW Statement?
2. What should the Relevant Equations be?
The HW statement is what you listed, and to solve it you use simple algebraic manipulations, so you probably don't need to list those (distributivity, associativity, etc.).

In the problem for this thread, the Relevant Equations/Information would be something like:

Parallel Lines: Have the same slope
Perpendicular Lines: Have inverse slopes
 
  • #7
36,856
8,896
Say the problem is solve y = mx + b for b.

1. What is the HW Statement?
2. What should the Relevant Equations be?
Homework Statement: solve y = mx + b for b
For this trivial example, I'd be fine with leaving the Relevant Equations section blank.
In the problem for this thread, the Relevant Equations/Information would be something like:

Parallel Lines: Have the same slope
Perpendicular Lines: Have inverse negative reciprocal slopes
Fixed that for you... :oldbiggrin:
 
  • #8
Homework Statement: solve y = mx + b for b
For this trivial example, I'd be fine with leaving the Relevant Equations section blank.

Fixed that for you... :oldbiggrin:
You are making a big deal about the HW Statement and Relevant Equations sections. Honestly, solving math problems is more important.
 
  • #9
36,856
8,896
You are making a big deal about the HW Statement and Relevant Equations sections.
Yes, because it shows us that you know exactly what the problem is, and what tools (equations, formulas, etc.) are going to be needed.

A case in point was your thread about proving that the diagonals of a parallelogram intersect at their midpoints. If you had written the formulas for distance between points and the midpoint of a line segment in the Relevant Equations section, that would have been strong evidence that you knew what to do. Since you didn't do so, helpers had to ask you if you knew both of these formulas.

Honestly, solving math problems is more important.
Solving the problem is important, but without a clear understanding of what the problem is about, and the tools you can use to solve it, it's extremely unlikely that you'll be able to solve the problem.
 

Suggested for: Parallel, Perpendicular, or Neither

  • Last Post
Replies
13
Views
613
  • Last Post
Replies
6
Views
809
Replies
12
Views
631
  • Last Post
Replies
7
Views
171
  • Last Post
Replies
6
Views
1K
Replies
3
Views
2K
Replies
1
Views
537
  • Last Post
Replies
5
Views
797
  • Last Post
Replies
6
Views
969
Top