0=4.905x^2+7.1685468561x-0.65

Solution for 0=4.905x^2+7.1685468561x-0.65 equation:

0=4.905x^2+7.1685468561x-0.65

We move all terms to the left:

0-(4.905x^2+7.1685468561x-0.65)=0

We add all the numbers together, and all the variables

-(4.905x^2+7.1685468561x-0.65)=0

We get rid of parentheses

-4.905x^2-7.1685468561x+0.65=0

a = -4.905; b = -7.1685468561; c = +0.65;
Δ = b2-4ac
Δ = -7.16854685612-4·(-4.905)·0.65
Δ = 64.1410640281
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7.1685468561)-\sqrt{64.1410640281}}{2*-4.905}=\frac{7.1685468561-\sqrt{64.1410640281}}{-9.81}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7.1685468561)+\sqrt{64.1410640281}}{2*-4.905}=\frac{7.1685468561+\sqrt{64.1410640281}}{-9.81}
$