0.45x^2-1.55x-1=0

Solution for 0.45x^2-1.55x-1=0 equation:

0.45x^2-1.55x-1=0

a = 0.45; b = -1.55; c = -1;
Δ = b2-4ac
Δ = -1.552-4·0.45·(-1)
Δ = 4.2025
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{-(-1.55)-\sqrt{4.2025}}{2*0.45}=\frac{1.55-\sqrt{4.2025}}{0.9}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.55)+\sqrt{4.2025}}{2*0.45}=\frac{1.55+\sqrt{4.2025}}{0.9}
$