20y^2-60y-80=0

Solution for 20y^2-60y-80=0 equation:

20y^2-60y-80=0

a = 20; b = -60; c = -80;
Δ = b2-4ac
Δ = -602-4·20·(-80)
Δ = 10000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{10000}=100$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-60)-100}{2*20}=\frac{-40}{40}
=-1
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-60)+100}{2*20}=\frac{160}{40}
=4
$