50=0,006v^2+0,3v

Solution for 50=0,006v^2+0,3v equation:

50=0.006v^2+0.3v

We move all terms to the left:

50-(0.006v^2+0.3v)=0

We get rid of parentheses

-0.006v^2-0.3v+50=0

a = -0.006; b = -0.3; c = +50;
Δ = b2-4ac
Δ = -0.32-4·(-0.006)·50
Δ = 1.29
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-0.3)-\sqrt{1.29}}{2*-0.006}=\frac{0.3-\sqrt{1.29}}{-0.012}
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.3)+\sqrt{1.29}}{2*-0.006}=\frac{0.3+\sqrt{1.29}}{-0.012}
$