We know that an integer is said to be even when it is divisible by 2.

Let m be a integer i.e. m = -1, 0, 1, 2, 3, 4,…..

Multiplying both the sides by 2

⇒ 2m = -2, 0, 2, 4, 6, 8,.……

Adding 1 on both the sides

⇒ 2m + 1 = -2 + 1, 0 + 1, 2 + 1, 4 + 1, 6 + 1, 8 + 1,…..

⇒ 2m + 1 = -1, 1, 3, 5, 7, 9,….

Hence, for some integer m, every even integer is of the form 2m.