Carcass wrote:
If K is an odd integer, which of the following is an odd integer?
(A) \(K^3 - 3 \)
(B) \(K^2 + 1 \)
(C) \((K + 1)^2 \)
(D) \(K^2 -1 \)
(E) \((K + 2)(K - 2) \)
Let's plug in a nice odd value for K.
The easiest will be K = 1.
We get....
(A) \(1^3 - 3 = -2\).
No good; we want an ODD value. (B) \(1^2 + 1 = 2\).
No good; we want an ODD value. (C) \((1 + 1)^2 = 4 \).
No good; we want an ODD value. (D) \(1^2 -1 = 0\).
No good; we want an ODD value. (E) \((1 + 2)(1 - 2) = -1\)
Perfect!Answer: E