Vieta theorem

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For the mentioned quadratic equation (i.e that, which coefficient (in case x2 is in it) is equal to figure one) x2 + px + q = 0 root sum is equal to coefficient p which is drawn with the opposite sign and root’s product is equal to free term q:
x1 + x2 = -p
x1x2 = q

In case of unreduced quadratic equation ax2 + bx + c = 0:
x1 + x2 = -b / a
x1x2 = c / a

In order not to make calculations manually just put values of coefficients into the set out below form.

Equation x2 + x + = 0
The result:

Discriminant D =
Roots x1 = x2 =

You can use Vieta theorem for roots finding of quadratic equation.