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

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The discussion revolves around determining the correct parametric and vector equations for the line defined by x = -1 + 5t and plotting it for specific values of t. Participants express confusion about the relationship between the given equations and the derived parametric forms, particularly regarding the use of different parameters (t vs. s). There is a focus on ensuring the equations are correctly formatted and that the graph accurately represents the line. The need to clarify the problem statement and resolve the discrepancies in parameter usage is emphasized. Ultimately, the goal is to find the correct expressions and plot the line accurately.
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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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