1=0.4k^2

Solution for 1=0.4k^2 equation:

1=0.4k^2

We move all terms to the left:

1-(0.4k^2)=0

We get rid of parentheses

-0.4k^2+1=0

a = -0.4; b = 0; c = +1;
Δ = b2-4ac
Δ = 02-4·(-0.4)·1
Δ = 1.6
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{1.6}}{2*-0.4}=\frac{0-\sqrt{1.6}}{-0.8}
=-\frac{\sqrt{}}{-0.8}
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{1.6}}{2*-0.4}=\frac{0+\sqrt{1.6}}{-0.8}
=\frac{\sqrt{}}{-0.8}
$