Question 147354
It is hard to tell from this problem to know 'where in algebra' you are. If you are just starting out, I suspect they are asking you to find the value(s) for k that allow simple factoring to work.

In that case, you will be looking for combinations of numbers whose product is 17 (since the coefficient of the x^2 term is 1). In that case, since 17 is prime, only 1 and 17 are possible factors. 
(x-17)(x-1) = x^2 -18x + 17
(x+17)(x+1) = x^2 +18 +17
So the only positive k would be 18

However, if you are farther along in algebra, then what you are being asked is "what vaues of k make the determinant of the solution to the quadratic equation greater than or equal to 0". If the term determinant is something you are learning or know, then use that to find the values of k. There are an infinite number; so use an inequality based on the the determinant being >= 0