Prove that the multiple of an even number and an odd number is always even.
2n is even, so (2n+1) is odd ; Multiplying even by odd gives: 2n(2n + 1) ; which is a multiple of 2, thus even * odd = even.
OT
2n is even, so (2n+1) is odd ; Multiplying even by odd gives: 2n(2n + 1) ; which is a multiple of 2, thus even * odd = even.