Find the equation of the plane that is tangent to the plane x = y² + z² - 2 on the point P(-1,1,0).
I got the equation x = 2y - 3 out of $F_{x}\Delta x + F_{y}\Delta y + F_{z}\Delta z = 0 $.
However this is a line, not a plane.
Are my calculations just plain wrong? Or if I did the math right, then what does this mean? Why do I get a line instead of a plane?
Your result is correct. The equation $x=2y-3$ is satisfied for any value of $z$ in $3D-$space and represents a plane parallel to the $z$ axis.