Question

How can you tell when a quadratic equation has two identical, rational solutions?

when the radicand is negative

when b in the quadratic formula is greater than the radicand

when the radicand equals zero

when the radicand is not a perfect square

Answer 1

If the radicand is 0 then the solution would like something like this:
\[x = -b +/- \sqrt{0}\]
-b + 0 = -b - 0
Which means that the roots are identical when the radicand is zero

Answer 2

so the 3rd one

Answer 3

Yes, thats correct!