Question

showthat n³-n is divisible by 6​

Answer 1

▶ Question :-

→ For any positive integer n, show that n³-n is divisible by 6​ .


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▶ Step-by-step explanation :-



▶ n³ - n = n (n² - 1) = n (n - 1) (n + 1)


Whenever a number is divided by 3, the remainder obtained is either 0 or 1 or 2.


∴ n = 3p or 3p + 1 or 3p + 2, where p is some integer.

If n = 3p, then n is divisible by 3.

If n = 3p + 1, then n – 1 = 3p + 1 –1 = 3p is divisible by 3.


If n = 3p + 2, then n + 1 = 3p + 2 + 1 = 3p + 3 = 3(p + 1) is divisible by 3.


So, we can say that one of the numbers among n, n – 1 and n + 1 is always divisible by 3.

⇒ n (n – 1) (n + 1) is divisible by 3.

Similarly, whenever a number is divided 2, the remainder obtained is 0 or 1.


∴ n = 2q or 2q + 1, where q is some integer.


If n = 2q, then n is divisible by 2.

If n = 2q + 1, then n – 1 = 2q + 1 – 1 = 2q is divisible by 2 and n + 1 = 2q + 1 + 1 = 2q + 2 = 2 (q + 1) is divisible by 2.

So, we can say that one of the numbers among n, n – 1 and n + 1 is always divisible by 2.


⇒ n (n – 1) (n + 1) is divisible by 2.

Since, n (n – 1) (n + 1) is divisible by 2 and 3.


∴ n ( n - 1 ) ( n + 1 ) = n³ - n is divisible by 6.( If a number is divisible by both 2 and 3 , then it is divisible by 6)



✔✔ Hence, it is solved ✅✅.



THANKS

Answer 2

ANSWER IN THE ATTACHMENT....