20-4.9x^2=0

Solution for 20-4.9x^2=0 equation:

20-4.9x^2=0

a = -4.9; b = 0; c = +20;
Δ = b2-4ac
Δ = 02-4·(-4.9)·20
Δ = 392
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:

$\sqrt{\Delta}=\sqrt{392}=\sqrt{196*2}=\sqrt{196}*\sqrt{2}=14\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-14\sqrt{2}}{2*-4.9}=\frac{0-14\sqrt{2}}{-9.8}
=-\frac{14\sqrt{2}}{-9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+14\sqrt{2}}{2*-4.9}=\frac{0+14\sqrt{2}}{-9.8}
=\frac{14\sqrt{2}}{-9.8}
$