Let P(x,y,z) be the point
Now, from perpendicular distance formula (x+y−z√3)2+(x+y−2z√6)2+(x−y√2)2=5
Therefore, x2+y2+z2=5
The equation of locus of a point where distance from the y-axis is equal to its distance from the point A(2,1,-1) is-