1-0.4x+0.004x^2=0

Solution for 1-0.4x+0.004x^2=0 equation:

1-0.4x+0.004x^2=0

a = 0.004; b = -0.4; c = +1;
Δ = b2-4ac
Δ = -0.42-4·0.004·1
Δ = 0.144
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{-(-0.4)-\sqrt{0.144}}{2*0.004}=\frac{0.4-\sqrt{0.144}}{0.008}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.4)+\sqrt{0.144}}{2*0.004}=\frac{0.4+\sqrt{0.144}}{0.008}
$