The plane x+y+z+k=0 touches the sphere x2+y2+z2 = k2 for:

all values of k/

no value/

finite values of k or

infinite no of values of k?

The plane touches the sphere iff it's perpendicular distance from centre is equal to radius.Thus,Distance=K/rt3=radius=KK=0

But when K=0,the sphere reduces to a point (0,0,0) And the plane reduces to x+y+z=0 which passes thro the origin.

What's the ans given,no value of k, is it?