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

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

-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}
$