#1**+2 **

(i) n(n-1)

If n-1 is odd, then n is even.

n(n-1) is the product of an even number and an odd number, so the product is even.

(ii) 2n=2*n Multiplying any whole number by 2 gives an even number, so 2n is an even number. So 2n+1=even number +1=odd number 2n+1 must always be an odd number.

lynx7
Feb 13, 2018