Prove that one of any three consecutive positive integers must be divisible by 3.

AcademicMathematicsNCERTClass 10

To do: 

We have to prove that one of any three consecutive positive integers must be divisible by 3.

Solution:

Let $a = n, b = n + 1$ and $c =n + 2$

Order triplet is $(a, b, c) = (n, n + 1, n + 2)$

where, $n$ is any positive integer

At $n = 1$ 

$(a, b, c) = (1, 1 + 1, 1 + 2)$

$= (1, 2, 3)$

At $n = 2$

$(a, b, c) = (2, 2 + 1, 2 + 2)$

$= (2, 3, 4)$

At $n = 3$ 

$(a, b,c) = (3, 3 + 1, 3 + 2)$

$= (3,4,5)$

At $n =4$   

$(a,b, c) =(4, 4 + 1, 4 +2)$

$= (4, 5, 6)$

At $n = 5$

$(a, b,c) = (5, 5 + 1, 5 +2)$

$= (5,6,7)$

At $n = 6$

$(a,b, c) = (6, 6 + 1, 6 + 2)$

$= (6,7,8)$

At $n = 7$

$(a, b,c) = (7, 7 +1, 7 + 2)$

$= (7,8,9)$

At $n = 8$ 

 $(a, b,c) =  (8,8+ 1, 8+ 2)$

$= (8,9,10)$

We observe that each triplet consists of one and only one number which is a multiple of 3.

Hence, one of any three consecutive positive integers must be divisible by 3.

raja
Updated on 10-Oct-2022 13:27:08

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