Question

Consider the following definition.
Definition. An integer n is sane if
3 | (n2 + 2n).
Give a counterexample to the following: All odd integers are sane.
n =

Answer 1

what do you get for n =1, n=3, n=5 ?

Answer 2

for n=1

n^2 +2n --> (1)^2+2(1) = 1+2 = 3

which is a multiple of 3,
so n=1 in not a counter example

Answer 3

incorrect

Answer 4

for n=3

n^2 + 2n --> 3^2 + 2(3) =

Answer 5

same, I wonder if I'm going to have to have the problem written out like the original one is

Answer 6

what do you get for the n=3 case?

Answer 7

@Scaleman

Answer 8

incorrect

Answer 9

what about the next smallest odd integer: n=5 ?

Answer 10

5^2+2(5) = ?

Answer 11

@Scaleman ?

Answer 12

is 5 sane?

Answer 13

Thank you very much for the help