Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 55)
55.
Which of the following numbers will completely divide (4915 - 1) ?
8
14
46
50
Answer: Option
Explanation:

(xn - 1) will be divisibly by (x + 1) only when n is even.

(4915 - 1) = {(72)15 - 1} = (730 - 1), which is divisible by (7 +1), i.e., 8.

Discussion:
16 comments Page 2 of 2.

Praneel said:   9 years ago
Agree @Rashid.

Sush said:   8 years ago
Can anyone please explain how to find 7 power 6-4 power 6 is divisible by?

Vicky said:   8 years ago
X^n-y^n=x-y.

So,
49^15-1^15=49-1=48.
48÷8....48 is divisible by 8 so, 8 is answer.

Zaki said:   6 years ago
Why not 50?

Gayathri Thota said:   5 years ago
(x^n-1) is divisible by x-1 when n is odd
Given
(49^15-1) is divisible by 49-1 i.e 48
48 is completely divisible by 8.(Here 15 is odd right)

Can we do it in this way?

Silverstar Tariang said:   5 years ago
a^n-b^n=a-b i.e 49-1=48 which is divisible by 8.

So the answer is 8.


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