0.4x2+0.8x=0.2

Solution for 0.4x2+0.8x=0.2 equation:

0.4x^2+0.8x=0.2

We move all terms to the left:

0.4x^2+0.8x-(0.2)=0

We add all the numbers together, and all the variables

0.4x^2+0.8x-0.2=0

a = 0.4; b = 0.8; c = -0.2;
Δ = b2-4ac
Δ = 0.82-4·0.4·(-0.2)
Δ = 0.96
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{-(0.8)-\sqrt{0.96}}{2*0.4}=\frac{-0.8-\sqrt{0.96}}{0.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.8)+\sqrt{0.96}}{2*0.4}=\frac{-0.8+\sqrt{0.96}}{0.8}
$