High school mathematics problems, a = {x = 2k-1, K ∈ Z}, B = {x = 2m + 1, m ∈ Z}, judge the relationship between the two sets More detailed process, thank you, I'm a novice

High school mathematics problems, a = {x = 2k-1, K ∈ Z}, B = {x = 2m + 1, m ∈ Z}, judge the relationship between the two sets More detailed process, thank you, I'm a novice

2k and 2m are even numbers
So 2k-1 and 2m + 1 are odd numbers
So a = B

Let two continuous even numbers be 2K + 2 and 2K (where k is a non negative integer). Is the mysterious number constructed by these two continuous even numbers a multiple of 4? Why?

(2k+2)²-(2k)²
=4(k+1)²-4*k²
=4[(k+1)²-k²]
=4(2k+1)
It's a multiple of four

The set of even numbers greater than - 3 and less than 11 is
｛x|-3

｛x|-3