I was assigned an achievement check a few days back and it is due soon.

Question: Find k such that the graph of y=9x^2 + 3kx + k:

a) intersects the x-axis in one point only

b) intersects the x-axis in two points

c) does not intersect the x-asix

I am unable to figure out how to solve it. Can someone explain to me how to do this please?