The question is:
Fr what value(s) of k will the function f(x)=(kx^2)-4x+k have no zeroes.
So for that, the discriminant would be less than 0.
So I know that I'm supposed to graph it with D as one axis an k as the other, and then shade the part of the graph that agrees with D<0, and use that to make the restrictions.
BUT I don't know whether the graph hs a minimum or maximum because I don't know the k value which is the a value that determines whether or not the graph has a minimum or maximum.
How do I finish this question?