C1 exam tormorrow, got some last minute questions.

5.The equation , where k is a constant, has no real roots.

Find the set of possible values of k.

So I use ?

If the question said:

5.The equation , where k is a constant, has equal roots.

I would use: ?

And if the question said

5.The equation , where k is a constant, 2 real roots.

I would use: ?