# Is this a linear equation xy=6?

If both $x$ and $y$ are variables, then the answer is: "No, it is not a linear equation.".
The linear equation is a sum of terms like "$A x$" where $x$ is a variable, and $A$ is a number or a constant.
On the other hand if $x$ or $y$ was a constant (like $e$ or $\pi$), it could be treated as a number and the whole expression would become linear.