-10y^2-20y+30=0

Solution for -10y^2-20y+30=0 equation:

-10y^2-20y+30=0

a = -10; b = -20; c = +30;
Δ = b2-4ac
Δ = -202-4·(-10)·30
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-40}{2*-10}=\frac{-20}{-20}
=1
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+40}{2*-10}=\frac{60}{-20}
=-3
$