# Thread: Cartesian Equation

1. ## Cartesian Equation

$x= 3t$
$y= 9t^2$

Find the cartesian equation.
I don't get what one is.

The answer is $t^2$.

thanks!

2. Originally Posted by Truthbetold
$x= 3t$
[tex]
The answer is $t^2$.
$t^2$ is not a cartesian equation. It's not even an equation..

As far as I know, cartesian equations are equations that describe the curve using x and y coordinates, not parameters like $t$.

$x = 3t$
$y = 9t^2$
You can see that $y = x^2$.

If you can't see the relation between x and y (parametric equations are not always simple like this), you can do it algebraically.

$x = 3t$
$t = \frac{x}{3}$
$y = 9t^2$
$y = 9 (\frac{x}{3})^2$
$y = x^2$