UNder what conditions would the well-known quadratoc formula?

Question

Roots= ((-b+- square root b^2-4ac))/2a

not be effectively computable? (Assume you are worling with real numbers)

Answer 1

When 4ac > b^2 you are dealing with imaginary roots, in that you are required to evaluate the square root of a negative number.  

Answer 2

"quadratic"

"working"

It's works under the condition that a,b,c are real numbers.

But the results may not be real, they can contain an imaginary component.

.