x2=0.4

Solution for x2=0.4 equation:

x2=0.4

We move all terms to the left:

x2-(0.4)=0

We add all the numbers together, and all the variables

x^2-0.4=0

a = 1; b = 0; c = -0.4;
Δ = b2-4ac
Δ = 02-4·1·(-0.4)
Δ = 1.6
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)-\sqrt{1.6}}{2*1}=\frac{0-\sqrt{1.6}}{2}
=-\frac{\sqrt{}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{1.6}}{2*1}=\frac{0+\sqrt{1.6}}{2}
=\frac{\sqrt{}}{2}
$