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Core 4: parametric equations

How do i find the cartesian equation of the line x=t^3+t and y=t^2-1
(edited 9 years ago)
Original post by James Cameron
How do i find the cartesian equation of the line x=t^3+t and y=t^2-1


Make t the subject of one formula (this looks easier to do for one equation rather than the other) and see where that gets you.
Original post by SeanFM
Make t the subject of one formula (this looks easier to do for one equation rather than the other) and see where that gets you.

t=sqrt y+1
Original post by James Cameron
t=sqrt y+1


Yep, now what should you do?
Original post by SeanFM
Yep, now what should you do?

sub it into x=t^3+t
this gives y=(sqrt y+1)^3 + sqrt y+1
not sure how to expand this though
Reply 5
Original post by James Cameron
sub it into x=t^3+t
this gives y=(sqrt y+1)^3 + sqrt y+1
not sure how to expand this though


I presume you mean x=?

You could start by taking out a factor of sqrt(y+1) which then simplifies reasonably agreeably.
Original post by Krollo
I presume you mean x=?

You could start by taking out a factor of sqrt(y+1) which then simplifies reasonably agreeably.

what was your final answer?

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