0=-401,6+39,2x+4.9x^2

Solution for 0=-401,6+39,2x+4.9x^2 equation:

0=-401.6+39.2x+4.9x^2

We move all terms to the left:

0-(-401.6+39.2x+4.9x^2)=0

We add all the numbers together, and all the variables

-(-401.6+39.2x+4.9x^2)=0

We get rid of parentheses

-4.9x^2-39.2x+401.6=0

a = -4.9; b = -39.2; c = +401.6;
Δ = b2-4ac
Δ = -39.22-4·(-4.9)·401.6
Δ = 9408
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:

$\sqrt{\Delta}=\sqrt{9408}=\sqrt{3136*3}=\sqrt{3136}*\sqrt{3}=56\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-39.2)-56\sqrt{3}}{2*-4.9}=\frac{39.2-56\sqrt{3}}{-9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-39.2)+56\sqrt{3}}{2*-4.9}=\frac{39.2+56\sqrt{3}}{-9.8}
$