0.4x^2-1.2x-0.36=0

Solution for 0.4x^2-1.2x-0.36=0 equation:

0.4x^2-1.2x-0.36=0

a = 0.4; b = -1.2; c = -0.36;
Δ = b2-4ac
Δ = -1.22-4·0.4·(-0.36)
Δ = 2.016
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{-(-1.2)-\sqrt{2.016}}{2*0.4}=\frac{1.2-\sqrt{2.016}}{0.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.2)+\sqrt{2.016}}{2*0.4}=\frac{1.2+\sqrt{2.016}}{0.8}
$