0=4.9x^2-2x-20

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

0=4.9x^2-2x-20

We move all terms to the left:

0-(4.9x^2-2x-20)=0

We add all the numbers together, and all the variables

-(4.9x^2-2x-20)=0

We get rid of parentheses

-4.9x^2+2x+20=0

a = -4.9; b = 2; c = +20;
Δ = b2-4ac
Δ = 22-4·(-4.9)·20
Δ = 396
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:

$\sqrt{\Delta}=\sqrt{396}=\sqrt{36*11}=\sqrt{36}*\sqrt{11}=6\sqrt{11}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-6\sqrt{11}}{2*-4.9}=\frac{-2-6\sqrt{11}}{-9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+6\sqrt{11}}{2*-4.9}=\frac{-2+6\sqrt{11}}{-9.8}
$