Question

How can you tell when a quadratic equation has two identical, rational solutions?
a:when the radicand is negative
b:when the radicand is not a perfect square
c:when b in the quadratic formula is greater than the radicand
d:when the radicand equals zero

Answer 1

Take a look at the quadratic formula.
\[\Large \frac{-b \pm \sqrt{b^2-4ac}}{2a}\]
Specifically, look at the square root part, and think about what will happen if that part is positive, if it's negative, or if it is 0.

Answer 2

If that part is positive, then you'll be able to take the square root, and you'll get two answers from it.
If that part is negative, then when I try to take the square root, I will get an imaginary number. =/
If that part is 0, then what is the square root of 0? 0. Plus or minus 0 gives me the same thing, so I end up with just one answer.

Answer 3

another note...identical roots happen in square of binomial ;)

Answer 4

the quadratic formula i love it

Answer 5

is it d?

Answer 6

yes it is..