20x^2-40x-25=0

Solution for 20x^2-40x-25=0 equation:

20x^2-40x-25=0

a = 20; b = -40; c = -25;
Δ = b2-4ac
Δ = -402-4·20·(-25)
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-60}{2*20}=\frac{-20}{40}
=-1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+60}{2*20}=\frac{100}{40}
=2+1/2
$