x^2+1.28x-0.36=0

Solution for x^2+1.28x-0.36=0 equation:

x^2+1.28x-0.36=0

a = 1; b = 1.28; c = -0.36;
Δ = b2-4ac
Δ = 1.282-4·1·(-0.36)
Δ = 3.0784
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{-(1.28)-\sqrt{3.0784}}{2*1}=\frac{-1.28-\sqrt{3.0784}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.28)+\sqrt{3.0784}}{2*1}=\frac{-1.28+\sqrt{3.0784}}{2}
$