0.0004-0.004x=x^2

Solution for 0.0004-0.004x=x^2 equation:

0.0004-0.004x=x^2

We move all terms to the left:

0.0004-0.004x-(x^2)=0

determiningTheFunctionDomain
-x^2-0.004x+0.0004=0

We add all the numbers together, and all the variables

-1x^2-0.004x+0.0004=0

a = -1; b = -0.004; c = +0.0004;
Δ = b2-4ac
Δ = -0.0042-4·(-1)·0.0004
Δ = 0.001616
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{-(-0.004)-\sqrt{0.001616}}{2*-1}=\frac{0.004-\sqrt{0.001616}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.004)+\sqrt{0.001616}}{2*-1}=\frac{0.004+\sqrt{0.001616}}{-2}
$