0=0.005x^2+0.23x-3

Solution for 0=0.005x^2+0.23x-3 equation:

0=0.005x^2+0.23x-3

We move all terms to the left:

0-(0.005x^2+0.23x-3)=0

We add all the numbers together, and all the variables

-(0.005x^2+0.23x-3)=0

We get rid of parentheses

-0.005x^2-0.23x+3=0

a = -0.005; b = -0.23; c = +3;
Δ = b2-4ac
Δ = -0.232-4·(-0.005)·3
Δ = 0.1129
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{-(-0.23)-\sqrt{0.1129}}{2*-0.005}=\frac{0.23-\sqrt{0.1129}}{-0.01}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.23)+\sqrt{0.1129}}{2*-0.005}=\frac{0.23+\sqrt{0.1129}}{-0.01}
$