A set of all positive integers divided by 5 and 1? The answer is {x ∈ n | x = 5K + 1, K ∈ n} Why should we explain the condition of K? Just explain the condition of element x? But the answer is not

A set of all positive integers divided by 5 and 1? The answer is {x ∈ n | x = 5K + 1, K ∈ n} Why should we explain the condition of K? Just explain the condition of element x? But the answer is not

{x∈N|x=5k+1}
First, for example, k = 0.2 does not meet the conditions
Second, your writing method is descriptive. The former is the form, and the latter is the condition. Your X ∈ n is also a condition, which is not standard. The condition should be written at the end
For example, {x | x = 5K + 1, X ∈ n}