Q.1 Show that n square minus 1 is divisible by 8 , if n is a odd positive integer?Q.2 Show that one and only one of n+1 . n+2 or n+4 is divisible by 3 when n is any positive integer.?

let n=2m+1, n²-1 =4m(m+1),either m or m+1 is surely even and is multiplied by 4. therefore n²-1 is divisible by 8 if nis odd

let n=3,it is easy to see that the second question is wrong.

Approved