6=-0.08x^2+1.6x-1

Solution for 6=-0.08x^2+1.6x-1 equation:

6=-0.08x^2+1.6x-1

We move all terms to the left:

6-(-0.08x^2+1.6x-1)=0

We get rid of parentheses

0.08x^2-1.6x+1+6=0

We add all the numbers together, and all the variables

0.08x^2-1.6x+7=0

a = 0.08; b = -1.6; c = +7;
Δ = b2-4ac
Δ = -1.62-4·0.08·7
Δ = 0.32
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{-(-1.6)-\sqrt{0.32}}{2*0.08}=\frac{1.6-\sqrt{0.32}}{0.16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.6)+\sqrt{0.32}}{2*0.08}=\frac{1.6+\sqrt{0.32}}{0.16}
$