0=-0.2x^2-0.2x+4

Solution for 0=-0.2x^2-0.2x+4 equation:

0=-0.2x^2-0.2x+4

We move all terms to the left:

0-(-0.2x^2-0.2x+4)=0

We add all the numbers together, and all the variables

-(-0.2x^2-0.2x+4)=0

We get rid of parentheses

0.2x^2+0.2x-4=0

a = 0.2; b = 0.2; c = -4;
Δ = b2-4ac
Δ = 0.22-4·0.2·(-4)
Δ = 3.24
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{-(0.2)-\sqrt{3.24}}{2*0.2}=\frac{-0.2-\sqrt{3.24}}{0.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.2)+\sqrt{3.24}}{2*0.2}=\frac{-0.2+\sqrt{3.24}}{0.4}
$