Question from text book. Hope can get right and clear answer. Steps are not necessary because I just want to check my own answer

Question 3 Consider a uniformly charged disk with radius R and total charge Q sitting in the cy-plane with its center at the origin. The electric field in the z-direction, Ez, at a distance d from the origin along the z-axis is given by 1 point Ez (d) = 2kQ 1 R2 R2 where k is Coulomb's constant. For large distances d away from the origin relative to the radius of the disk R, we have d > R or, equivalently, , A