Question

A variable plane at a distance of 1 unit from the origin cuts the co-ordinate axes at A, B and C. If the centroid D(x, y, z) of ΔABC satisfies the relation 1/x² + 1/y² + 1/z² = k, then k is 

(a) 1 

(b) 3 

(c) 9 

(d) 4

Answer 1

Answer is (c) 9

The equation of the plane is x/a + y/b + z/c = 1

Clearly, the distance from the origin to the plane is 1