20x^2-57x-9=0

Solution for 20x^2-57x-9=0 equation:

20x^2-57x-9=0

a = 20; b = -57; c = -9;
Δ = b2-4ac
Δ = -572-4·20·(-9)
Δ = 3969
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3969}=63$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-57)-63}{2*20}=\frac{-6}{40}
=-3/20
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-57)+63}{2*20}=\frac{120}{40}
=3
$