0=20-4.5x^2

Solution for 0=20-4.5x^2 equation:

0=20-4.5x^2

We move all terms to the left:

0-(20-4.5x^2)=0

We add all the numbers together, and all the variables

-(20-4.5x^2)=0

We get rid of parentheses

4.5x^2-20=0

a = 4.5; b = 0; c = -20;
Δ = b2-4ac
Δ = 02-4·4.5·(-20)
Δ = 360
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:

$\sqrt{\Delta}=\sqrt{360}=\sqrt{36*10}=\sqrt{36}*\sqrt{10}=6\sqrt{10}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-6\sqrt{10}}{2*4.5}=\frac{0-6\sqrt{10}}{9}
=-\frac{6\sqrt{10}}{9}
=-\frac{2\sqrt{10}}{3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+6\sqrt{10}}{2*4.5}=\frac{0+6\sqrt{10}}{9}
=\frac{6\sqrt{10}}{9}
=\frac{2\sqrt{10}}{3}
$