Question

How do I know if a quadratic equation has no real roots?

Answer 1

when discriminant is negative

Answer 2

If the discriminant, D = b^2-4ac is less than zero


For instance, the quadratic y=x^2+9 has no real roots since


D = b^2-4ac =(0)^2-4(1)(9) = -36 which is less than zero

Answer 3

for example this this equation have no real roots? x\[^{2}+16=0\]

Answer 4

yes, that equation has no real roots

Answer 5

since D = b^2-4ac = 0^2-4(1)(16)=0-64=-64 which is less than zero

Answer 6

How do i work it out to check if it has no real roots though? :O

Answer 7

x^2+16 = 0


x^2 = -16


x = +-sqrt(-16)


Since the square root of a negative number is not a real number, this means that there are no real roots

Answer 8

btw, the discriminant formula i showed above works just as well (if not better/faster)

Answer 9

Oh!! i understand now. Thank you so much!!

Answer 10

yw