10k2+20k-89=-9

Solution for 10k2+20k-89=-9 equation:

10k^2+20k-89=-9

We move all terms to the left:

10k^2+20k-89-(-9)=0

We add all the numbers together, and all the variables

10k^2+20k-80=0

a = 10; b = 20; c = -80;
Δ = b2-4ac
Δ = 202-4·10·(-80)
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-60}{2*10}=\frac{-80}{20}
=-4
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+60}{2*10}=\frac{40}{20}
=2
$