x^2+x-k
find all positive values for k, if it can be factored
Allowed values of k for for the expression to be factorable with integers are
a*(a+1)
where a is an integer equal to 1 or more.
For example: 2, 6, 12, 20...
The factors are
(x-a)(x+a+1)
There are also real non-integer values of k that allow factrs, as long as 1+4k >0