Quadratic equation is an equation of the form ax2 + bx + c = 0, where a is not equal to 0.
You can use the following formulas for solving quadratic equations:
and 
where D = b2 - 4ac — is a discriminant of a polynomial ax2 + bx + c.
If D > 0, then an equation has two different real roots.
If D = 0, then both roots are real and equal.
If D < 0, then both roots are complex numbers.
In order not to make calculations manually just put values of coefficients into the set out below form.
You can use Vieta theorem to find the roots of a quadratic equation.