CBSE Class 10 Answered

let the cons integers be

n-1, n , n+1, n+2, n+3, n+4...

suppose

n-1 is divi by 3

 then n-1=3p for some integer p.

 so

 n=3p+1

and

n+1=3p+2

 which clearly will leave a remainder of 1 and 2 respectively when divided by 3, so out of the first three numbers only n-1 is divisible by 3.

 the next numeber is n+2=3p+1+2=3p+3=3(p+1) which is clearly divi by 3.

similarly if n-1 is not divi by 3 then you can assume that n is divi by 3 and show that n+1 is also not divi by 3.

which will serve the purpose.

 hence the answer.