# Is this a linear equation y^2- 4x=6?

The answer depends on how you treat $x$ and $y$.
If they are both unknowns, then it is not a linear equation, because one of the unknowns ($y$) is raised to a power other than 1.
But on the other hand, if you treat $y$ as a constant (like $e$ or $\pi$) then the only variable ($x$) is raised to the power 1, and the equation becomes linear.