Answer:
Zero
Explanation:
because, if the Discriminant of f is positive, it intersects the x-axis twice; if it’s negative, it intersects the x axis 0 times, but if it intersects the x axis or touches it in 1 point, then the Discriminant is 0!
As you can see in this graph, the x-axis and parabola only touch/intersect in 1 point, so the Discriminant of f is zero
Hope this helps!