Carcass wrote:
n is an integer greater than 1. If the remainder is 1, when n is divided by 3, then (n^2 + n - 2) must be divisible by which of he following double-digit number?
A. 12
B. 14
C. 16
D. 18
E. 20
One approach....
If the remainder is 1, when n is divided by 3, then
n is 1 greater than some multiple of 3So, we can say
n = 3k + 1 for some integer k.
We want to find the value of n² + n - 2
Replace n with
3k + 1 to get: n² + n - 2 = (
3k + 1)² + (
3k + 1) - 2
Simplify to get: 9k² + 9k
Factor:
9(k² + k)
So, the correct answer must be a multiple of
9Answer: D
Cheers,
Brent