Converting parametric equations to implicit form when isolating t is difficult

  • Context: Undergrad 
  • Thread starter Thread starter Gagle The Terrible
  • Start date Start date
  • Tags Tags
    Parametric
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
4 replies · 4K views
Gagle The Terrible
Messages
39
Reaction score
0
I would like to convert these parametric equations into a single
f(x,y) = 0 function.

X(t) = t^2 + t + 1
Y(t) = t^2 - t +1

In fact, what stops me is the imaginary roots of the parametric polynomials.

Is there a way to get around the seemingly impossible explicit solving of the quadratics to isolate either X or Y ?
 
Mathematics news on Phys.org
Note that x - t = y + t (or just subtract y(t) from x(t)).
 
Last edited:
Gagle The Terrible said:
I would like to convert these parametric equations into a single
f(x,y) = 0 function.

X(t) = t^2 + t + 1
Y(t) = t^2 - t +1

In fact, what stops me is the imaginary roots of the parametric polynomials.

Is there a way to get around the seemingly impossible explicit solving of the quadratics to isolate either X or Y ?

First note that X - Y = 2t, but also notice that these are both quadratic equations so you can solve one of them or the other to find t in terms of X or Y and then substitute this into X - Y = 2t or the equation for the other variable.
 
You just want to substitute t = (x - y) / 2. There's no need to solve any quadratics.
 
0rthodontist said:
You just want to substitute t = (x - y) / 2. There's no need to solve any quadratics.

Darn, I guess I should have seen that since I did notice that x - y = 2t.