0.16x=0.04x^2

Solution for 0.16x=0.04x^2 equation:

0.16x=0.04x^2

We move all terms to the left:

0.16x-(0.04x^2)=0

We get rid of parentheses

-0.04x^2+0.16x=0

a = -0.04; b = 0.16; c = 0;
Δ = b2-4ac
Δ = 0.162-4·(-0.04)·0
Δ = 0.0256
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{-(0.16)-\sqrt{0.0256}}{2*-0.04}=\frac{-0.16-\sqrt{0.0256}}{-0.08}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.16)+\sqrt{0.0256}}{2*-0.04}=\frac{-0.16+\sqrt{0.0256}}{-0.08}
$