x^2-0.4x-0.02=0

Solution for x^2-0.4x-0.02=0 equation:

x^2-0.4x-0.02=0

a = 1; b = -0.4; c = -0.02;
Δ = b2-4ac
Δ = -0.42-4·1·(-0.02)
Δ = 0.24
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{0.24}}{2*1}=\frac{0.4-\sqrt{0.24}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.4)+\sqrt{0.24}}{2*1}=\frac{0.4+\sqrt{0.24}}{2}
$