Parametic y= sqrt(t +1) and y = sqrt(t-1)

[Jbreezy]

Homework Statement

I have to eliminate the parameter and write in Cartesian form.

Homework Equations

y= sqrt(t +1) and y = sqrt(t-1)

The Attempt at a Solution

If you were to just go for the gusto and square it out you will end up with 0 = 2. Clearly I'm missing something here. Just stumped. I don't think the right way to go is squaring and setting them equal.

 

[cepheid]

Can you post the *exact* problem statement please?

 

[Jbreezy]

Yep,

Eliminate the parameter to find a Cartesian equation of the curve.

y = sqrt(t +1) , y = sqrt(t -1)

 

[cepheid]

I think perhaps one of the y's is supposed to be an x.

 

[Jbreezy]

Ha It is possible. There was a misprint on one of the graphs where it was supposed to say seconds and it was like hours. So I suppose. I just didn't know if I was missing something. Seems like you would just do as I said and square it and yatta but you get 0 = 2.

 

[cepheid]

Unless I am missing something obvious, I don't think it has a solution as given.

 

[Jbreezy]

Not sure maybe someone else has ideas too?

 

[Dick]

Not sure maybe someone else has ideas too?

Yeah, cepheid is right. There is clearly a typo in the problem. It's just expressing y in terms of two contradictory equations in t. There should be an x in there somewhere.

 

[HallsofIvy]

Homework Statement

I have to eliminate the parameter and write in Cartesian form.

Homework Equations

y= sqrt(t +1) and y = sqrt(t-1)

The Attempt at a Solution

If you were to just go for the gusto and square it out you will end up with 0 = 2. Clearly I'm missing something here. Just stumped. I don't think the right way to go is squaring and setting them equal.

These are NOT "parametric equations" and CANNOT be put in "Cartesian" form without an "x". As others have suggested, it must be x= \sqrt{t+ 1} and y= \sqrt{t- 1}. Yes, square both, then solve for t and set the two equations for t equal.

 

[Jbreezy]

OK then there is a typo in my book. Thanks for the help I will bring it up in lecture.