kiran120680 wrote:
If n is a positive integer, which of the following must be divisible by 12?
I. n^4–n^2
II. (n-6)^2(n-4)(n+13)^2
III. 2n(n-10)(n+13)
A. I and II only
B. II and III only
C. I and III only
D. I, II and III
E. None of the above
which of the following "must be" not definitely .so substitute random numbers in the
I. n^4–n^2: n^2(n-1)(n+1)
take n = 4
4^2 * 3 * 5.....it is divisible by 12
(n-6)^2(n-4)(n+13)^2take n = 12
6^2*2*19.......divisible by 12
2n(n-10)(n+13)take n =12
2*12*2*25......divisible by 12
so the answer is all three...option:
D