The implicitplot command computes the two-dimensional plot of an implicitly defined curve.

The invalid input: the following extra unknowns were found in the input expression error occurs when an unknown variable in the first argument is passed to the implicitplot command.

Example 1

Lowercase $\mathrm{pi}$ is used instead of uppercase $\mathrm{Pi}$.

Solution:

Example 2

In the following example, an extra space has been entered between $\sec$$\mathit{ }$and $\left(x^2 \+ y^2\right)$.

Solution:

Remove the extra space between $\sec$$\mathit{ }$and $\left(x^2 \+ y^2\right)$.

Example 3

In the following example, the implicitplot command is used incorrectly to plot an equation in three variables.

Solution:

Plot the equation in three variables using the plots[implicitplot3d] command