Is this the correct graph for x=-1+5t when t = −2, −1, 0, 1 and 2?

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Homework Help Overview

The discussion revolves around the parametric and vector equations of a line represented by the equation x = -1 + 5t, with a focus on plotting the graph for specific values of t: -2, -1, 0, 1, and 2. Participants are examining the relationship between this equation and another set of symmetric equations involving x, y, and z.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the derivation of parametric equations and question the validity of the expressions for x in terms of different parameters. There is an exploration of how to substitute x = -1 + 5t into the symmetric equations and what implications this has for finding y and z.

Discussion Status

Some participants have provided guidance on how to approach the substitution and the implications of using different parameters. There is an ongoing exploration of the relationships between the equations and the plotting of points, with no explicit consensus reached on the correct approach.

Contextual Notes

Participants express concerns about the clarity of the problem statement and the potential confusion arising from the use of different parameters for the equations. There is a noted ambiguity regarding the interpretation of the symmetric equations and their relationship to the parametric form.

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Homework Statement



Write the parametric and vector equations of:

x + 2 / 3 = y − 1 / 2 = z + 5/ -3

x=-1+5t
and plot a graph of this line when t = −2, −1, 0, 1 and 2.

Homework Equations



vector:
r= [-2,1,-5]+t[3,2,-3]
parametric
x=3t-2
y=2t+1
z=-3t-5

using parametric equation:: i drew the graph, please check if the graph is correct at -2,-1,0,1,,2

The Attempt at a Solution

 

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f22archrer said:

Homework Statement



Write the parametric and vector equations of:

x + 2 / 3 = y − 1 / 2 = z + 5/ -3

x=-1+5t
and plot a graph of this line when t = −2, −1, 0, 1 and 2.

Homework Equations



vector:
r= [-2,1,-5]+t[3,2,-3]
parametric
x=3t-2
y=2t+1
z=-3t-5

using parametric equation:: i drew the graph, please check if the graph is correct at -2,-1,0,1,,2

The Attempt at a Solution


Not sure where that x = -1+5t came from. But your parametric equations look correct. I didn't check all your points, but if you plotted the points to scale as apparently you did, and they came out on a straight line, aren't you pretty confident in the answers?
 
actually i was worried about the axis ... in specific the z axis.. i just had this gut feeling like i took -z the wrong direction ...
 
x=-1+5t is part of the question .
 
f22archrer said:
Write the parametric and vector equations of:

x + 2 / 3 = y − 1 / 2 = z + 5/ -3

Based on your subsequent work, your symmetric equations need parentheses.

Here are the equations, using LaTeX.

$$ \frac{x + 2}{3} = \frac{y - 1}{2} = \frac{z + 5}{-3}$$

When you write them in plain text, they should look like this:

(x + 2)/3 = (y - 1)/2 = (z + 5)/(-3)

What you wrote means the following:
x + ##\frac{2}{3}## = y - ##\frac{1}{2}## = z + ##\frac{5}{-3}##
 
f22archrer said:
x=-1+5t is part of the question .

Then doesn't it seem odd that you are saying x=3t-2 in the solution? I assume when you are writing "x + 2 / 3" you mean (x+2)/3, not x+(2/3). But even assuming that, your parametric form looks screwed up. Put x=(-1)+5t into (x+2)/3=(y-1)/2 and solve for y in terms of t. The 't' in your equations is the wrong parameter. Your are going to get the same line, but the points corresponding to a given value of t will be different.
 
Last edited:
hey , sorry for late response but if i put x=-1+5t in [x+2]/3= [y-1]/2=[z+5]/-3 what will i get after... how do i solve for y
 
f22archrer said:
hey , sorry for late response but if i put x=-1+5t in [x+2]/3= [y-1]/2=[z+5]/-3 what will i get after... how do i solve for y
Are you asking how to solve
\displaystyle \frac{(-1+5t)+2}{3}=\frac{y-1}{2}​
for y ?

Give it a try.

What do you get?
 
i didnt mean how i will solve it..rather i was concerned about what too do after i get the Y value


y =[5+10t]/3
 
  • #10
f22archrer said:
i didnt mean how i will solve it..rather i was concerned about what too do after i get the y value

y =[5+10t]/3
That depends.

What is it you're trying to do next?
 
  • #11
f22archrer said:
x=-1+5t is part of the question .
Then you have two different expessions for x a function of t. What are you supposed to use?
 
  • #12
next i need to find vector and parametric equation and then plot for t ...|
 
  • #13
This seems like a very strange way to phrase the problem, making me wonder what the exact statement of the problem is.

f22archrer said:

Homework Statement



Write the parametric and vector equations of:

x + 2 / 3 = y − 1 / 2 = z + 5/ -3

x=-1+5t
and plot a graph of this line when t = −2, −1, 0, 1 and 2.

Homework Equations



vector:
r= [-2,1,-5]+t[3,2,-3]
parametric
x=3t-2
y=2t+1
z=-3t-5

Taking the problem as you have quoted, don't use ##t## here. You apparently should write:
x=3s-2
y=2s+1
z=-3s-5
using s for your parameter. Now if x = -1+5t you can put that in and get s in terms of t. Then use that in these last three equations. Of course, this all assumes I understand what you are trying to do.
 

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