20x2-9x-20=0

Solution for 20x2-9x-20=0 equation:

20x^2-9x-20=0

a = 20; b = -9; c = -20;
Δ = b2-4ac
Δ = -92-4·20·(-20)
Δ = 1681
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1681}=41$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-41}{2*20}=\frac{-32}{40}
=-4/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+41}{2*20}=\frac{50}{40}
=1+1/4
$