Describe in words the region of double-struck r3 represented by the equations or inequalities. x2 + z2 ≤ 9 here x2 + z2 ≤ 9 or equivalently x2 + z2 ≤ 3 which describes the set of all points in double-struck r3 whose distance from the -axis is at most 3 . thus, the inequality represents the region consisting of all points on or inside a of radius with axis the -axis.