0=0.2x2-10

Solution for 0=0.2x2-10 equation:

0=0.2x^2-10

We move all terms to the left:

0-(0.2x^2-10)=0

We add all the numbers together, and all the variables

-(0.2x^2-10)=0

We get rid of parentheses

-0.2x^2+10=0

a = -0.2; b = 0; c = +10;
Δ = b2-4ac
Δ = 02-4·(-0.2)·10
Δ = 8
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{8}=\sqrt{4*2}=\sqrt{4}*\sqrt{2}=2\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-2\sqrt{2}}{2*-0.2}=\frac{0-2\sqrt{2}}{-0.4}
=-\frac{2\sqrt{2}}{-0.4}
=-\frac{\sqrt{2}}{-0.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+2\sqrt{2}}{2*-0.2}=\frac{0+2\sqrt{2}}{-0.4}
=\frac{2\sqrt{2}}{-0.4}
=\frac{\sqrt{2}}{-0.2}
$