Use expressions for odd integers to confirm the conjecture that the product for two odd integers is an odd integer.

2n + 1 et 2n + 3 are two odd integers with n integer

(2n+1) (2n+3) = 4n² + 8n + 3 = 2 (4n² + 4n) + 3

2 (4n² + 4n) is an even integer so 2 (4n² + 4n) + 3 is an odd number

because the sum of an even number and an odd number is an odd number.