18a^2+9a-20=0

Solution for 18a^2+9a-20=0 equation:

18a^2+9a-20=0

a = 18; b = 9; c = -20;
Δ = b2-4ac
Δ = 92-4·18·(-20)
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-39}{2*18}=\frac{-48}{36}
=-1+1/3
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+39}{2*18}=\frac{30}{36}
=5/6
$