Question

A discriminant of 0 indicates what type of roots?
Answer
Two Rational
Two Complex
One Rational Double
Two Irrational

Answer 1

Well, look at an example:
x^2 - 2x + 1

The discriminant = 2^2 - 4(1)(1) = 4 - 4 =0

and x^2 - 2x + 1 = (x-1)^2 => x = 1 is a double root

So it looks like discriminant = 0 means .... what?