x^2+0.40x-0.09=0

Solution for x^2+0.40x-0.09=0 equation:

x^2+0.40x-0.09=0

a = 1; b = 0.40; c = -0.09;
Δ = b2-4ac
Δ = 0.402-4·1·(-0.09)
Δ = 0.52
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{-(0.40)-\sqrt{0.52}}{2*1}=\frac{-0.4-\sqrt{0.52}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.40)+\sqrt{0.52}}{2*1}=\frac{-0.4+\sqrt{0.52}}{2}
$