x^2-0.86*x-0.043=0

Solution for x^2-0.86*x-0.043=0 equation:

x^2-0.86x-0.043=0

a = 1; b = -0.86; c = -0.043;
Δ = b2-4ac
Δ = -0.862-4·1·(-0.043)
Δ = 0.9116
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{-(-0.86)-\sqrt{0.9116}}{2*1}=\frac{0.86-\sqrt{0.9116}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.86)+\sqrt{0.9116}}{2*1}=\frac{0.86+\sqrt{0.9116}}{2}
$