6x-0,25x^2=20

Solution for 6x-0,25x^2=20 equation:

6x-0.25x^2=20

We move all terms to the left:

6x-0.25x^2-(20)=0

a = -0.25; b = 6; c = -20;
Δ = b2-4ac
Δ = 62-4·(-0.25)·(-20)
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-4}{2*-0.25}=\frac{-10}{-0.5}
=+20
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+4}{2*-0.25}=\frac{-2}{-0.5}
=+4
$