-x^2-1.80x+0.17802=0

Solution for -x^2-1.80x+0.17802=0 equation:

-x^2-1.80x+0.17802=0

We add all the numbers together, and all the variables

-1x^2-1.8x+0.17802=0

a = -1; b = -1.8; c = +0.17802;
Δ = b2-4ac
Δ = -1.82-4·(-1)·0.17802
Δ = 3.95208
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{-(-1.8)-\sqrt{3.95208}}{2*-1}=\frac{1.8-\sqrt{3.95208}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.8)+\sqrt{3.95208}}{2*-1}=\frac{1.8+\sqrt{3.95208}}{-2}
$