0.2x(x+2)-0.4(x+2)=-0.2x-0.4

Solution for 0.2x(x+2)-0.4(x+2)=-0.2x-0.4 equation:

0.2x(x+2)-0.4(x+2)=-0.2x-0.4

We move all terms to the left:

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

We multiply parentheses

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

We get rid of parentheses

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

We add all the numbers together, and all the variables

x^2+0.8x-0.4=0

a = 1; b = 0.8; c = -0.4;
Δ = b2-4ac
Δ = 0.82-4·1·(-0.4)
Δ = 2.24
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{-(0.8)-\sqrt{2.24}}{2*1}=\frac{-0.8-\sqrt{2.24}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.8)+\sqrt{2.24}}{2*1}=\frac{-0.8+\sqrt{2.24}}{2}
$