0,9x+0,3x2=0

Solution for 0,9x+0,3x2=0 equation:

0.9x+0.3x^2=0

a = 0.3; b = 0.9; c = 0;
Δ = b2-4ac
Δ = 0.92-4·0.3·0
Δ = 0.81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0.9)-\sqrt{0.81}}{2*0.3}=\frac{-0.9-\sqrt{0.81}}{0.6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.9)+\sqrt{0.81}}{2*0.3}=\frac{-0.9+\sqrt{0.81}}{0.6}
$