0.15x+0.05-0.25x^2=0

Solution for 0.15x+0.05-0.25x^2=0 equation:

0.15x+0.05-0.25x^2=0

a = -0.25; b = 0.15; c = +0.05;
Δ = b2-4ac
Δ = 0.152-4·(-0.25)·0.05
Δ = 0.0725
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{-(0.15)-\sqrt{0.0725}}{2*-0.25}=\frac{-0.15-\sqrt{0.0725}}{-0.5}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.15)+\sqrt{0.0725}}{2*-0.25}=\frac{-0.15+\sqrt{0.0725}}{-0.5}
$