0.2x^2-10x-800=0

Solution for 0.2x^2-10x-800=0 equation:

0.2x^2-10x-800=0

a = 0.2; b = -10; c = -800;
Δ = b2-4ac
Δ = -102-4·0.2·(-800)
Δ = 740
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{740}=\sqrt{4*185}=\sqrt{4}*\sqrt{185}=2\sqrt{185}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-2\sqrt{185}}{2*0.2}=\frac{10-2\sqrt{185}}{0.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+2\sqrt{185}}{2*0.2}=\frac{10+2\sqrt{185}}{0.4}
$