solution:
R = {(a, b) : a ≤ b3}
a ≤ a3: which is valid, (a, a) ∉ R, So R isn’t reflexive.
a ≤ b3 however b ≤ a3 (bogus): (a, b) ∈ R yet (b, a) ∉ R, So R isn’t symmetric.
Once more, a ≤ b3 and b ≤ c3 then a ≤ c3 (bogus) : (a, b) ∈ R and (b, c) ∈ R and (a, c) ∉ R, So R is transitive.
In this manner, R is neither reflexive, nor transitive and nor symmetric.