x^2-0.3x-0.15^2=0

Solution for x^2-0.3x-0.15^2=0 equation:

x^2-0.3x-0.15^2=0

We add all the numbers together, and all the variables

x^2-0.3x-0.0225=0

a = 1; b = -0.3; c = -0.0225;
Δ = b2-4ac
Δ = -0.32-4·1·(-0.0225)
Δ = 0.18
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{-(-0.3)-\sqrt{0.18}}{2*1}=\frac{0.3-\sqrt{0.18}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.3)+\sqrt{0.18}}{2*1}=\frac{0.3+\sqrt{0.18}}{2}
$