Question

Show that one and only one out of n n+1 is divisible by 3

Answer 1

Step-by-step explanation:

let n be divisible by 3 then

n=3Q where Q is quotient Q belongs to Integer

let n+1 also divisible by 3 then

n+1=3P where p is also quotient where Q belongs to Integer by observation P>Q

puting value of n

3Q + 1=3P

1=3(P-Q)

p-q>1 so lhs is not rhs

hence only 1 of n or n+1 is divisible by 3