x=2k+ 1? K∈Z, which means that X takes odd numbers in all integers ...-9,-7,-5,-3,-1,1,3, 5, 7, 9, .....
x = 4k 1 = 2(2k 1)- 1? K∈Z means that x takes some odd numbers in the integer? ....-9,-7,5,- 1, 1,5,7,9, .....
It's obvious? A=B? Again, the second question? N is also a partial even number, and m is a full even number, so? MN。