-1.8x^2-6.6x+1=0

Solution for -1.8x^2-6.6x+1=0 equation:

-1.8x^2-6.6x+1=0

a = -1.8; b = -6.6; c = +1;
Δ = b2-4ac
Δ = -6.62-4·(-1.8)·1
Δ = 50.76
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{-(-6.6)-\sqrt{50.76}}{2*-1.8}=\frac{6.6-\sqrt{50.76}}{-3.6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6.6)+\sqrt{50.76}}{2*-1.8}=\frac{6.6+\sqrt{50.76}}{-3.6}
$