0=-0.6x^2+0.8x+3

Solution for 0=-0.6x^2+0.8x+3 equation:

0=-0.6x^2+0.8x+3

We move all terms to the left:

0-(-0.6x^2+0.8x+3)=0

We add all the numbers together, and all the variables

-(-0.6x^2+0.8x+3)=0

We get rid of parentheses

0.6x^2-0.8x-3=0

a = 0.6; b = -0.8; c = -3;
Δ = b2-4ac
Δ = -0.82-4·0.6·(-3)
Δ = 7.84
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{-(-0.8)-\sqrt{7.84}}{2*0.6}=\frac{0.8-\sqrt{7.84}}{1.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.8)+\sqrt{7.84}}{2*0.6}=\frac{0.8+\sqrt{7.84}}{1.2}
$