Question

If a and b are integers, when is 1/ab positive?

Answer 1

a*b is only positive if

both a and b are positive

OR

both a and b are negative

Answer 2

1/(a*b) is only positive when a*b is positive (since 1 is positive)

Answer 3

Thanks, what about -1/a, when is that positive?

Answer 4

well if 'a' was positive, then -a is negative

1/a is positive when 'a' is positive

so -1/a is positive when 'a' is negative