0=0.2x2+3x-20

Solution for 0=0.2x2+3x-20 equation:

0=0.2x^2+3x-20

We move all terms to the left:

0-(0.2x^2+3x-20)=0

We add all the numbers together, and all the variables

-(0.2x^2+3x-20)=0

We get rid of parentheses

-0.2x^2-3x+20=0

a = -0.2; b = -3; c = +20;
Δ = b2-4ac
Δ = -32-4·(-0.2)·20
Δ = 25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25}=5$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-5}{2*-0.2}=\frac{-2}{-0.4}
=+5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+5}{2*-0.2}=\frac{8}{-0.4}
=-20
$