Respuesta :
The rule, letting d=discriminant:
d>0, two real solutions
d=0, one real solution
d<0, no real solution (but there are two imaginary solutions)
So if it has only one real solution, the discriminant is equal to zero.
d>0, two real solutions
d=0, one real solution
d<0, no real solution (but there are two imaginary solutions)
So if it has only one real solution, the discriminant is equal to zero.