-1.6x2-3.2x+18=0

Solution for -1.6x2-3.2x+18=0 equation:

-1.6x^2-3.2x+18=0

a = -1.6; b = -3.2; c = +18;
Δ = b2-4ac
Δ = -3.22-4·(-1.6)·18
Δ = 125.44
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{-(-3.2)-\sqrt{125.44}}{2*-1.6}=\frac{3.2-\sqrt{125.44}}{-3.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3.2)+\sqrt{125.44}}{2*-1.6}=\frac{3.2+\sqrt{125.44}}{-3.2}
$