Should be smaller equal to 0. One repeated root means touching at one point and doesn’t go below x-axis ie never negative.

Also must note that “k” has to be positive.

If k is negative, it’s a “n” shape which will mean a part of the graph is under the x-axis ie negative.

If k is positive, itll be a “u” shape and if the “u” shape is touching or above the x-axis means that it’s fully non-negative.

This kind of question must take extra care.

You are right. My mistake :)