Write the following sets iroster from: K = {x : ϵ N, x is a multiple of 5 and x 2

Question

Write the following sets iroster from: K = {x : ϵ N, x is a multiple of 5 and x 2 < 400}.

Philoid · Accepted Answer

Multiple of 5 are 5, 10, 15, 20, 25, 30, …

So, 5² = 25

10² = 100

15² = 225

20² = 400

25² = 625 > 400

The elements which are multiple of 5 and x² < 400 are 5, 10, 15

So, K = {5, 10, 15}