0.25=0.4*x+0.25*x^2

Solution for 0.25=0.4*x+0.25*x^2 equation:

0.25=0.4*x+0.25*x^2

We move all terms to the left:

0.25-(0.4*x+0.25*x^2)=0

We get rid of parentheses

-0.4*x-0.25*x^2+0.25=0

We add all the numbers together, and all the variables

-0.25x^2-0.4x+0.25=0

a = -0.25; b = -0.4; c = +0.25;
Δ = b2-4ac
Δ = -0.42-4·(-0.25)·0.25
Δ = 0.41
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{-(-0.4)-\sqrt{0.41}}{2*-0.25}=\frac{0.4-\sqrt{0.41}}{-0.5}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.4)+\sqrt{0.41}}{2*-0.25}=\frac{0.4+\sqrt{0.41}}{-0.5}
$