3=-0.1x^2+1.1x+2

Solution for 3=-0.1x^2+1.1x+2 equation:

3=-0.1x^2+1.1x+2

We move all terms to the left:

3-(-0.1x^2+1.1x+2)=0

We get rid of parentheses

0.1x^2-1.1x-2+3=0

We add all the numbers together, and all the variables

0.1x^2-1.1x+1=0

a = 0.1; b = -1.1; c = +1;
Δ = b2-4ac
Δ = -1.12-4·0.1·1
Δ = 0.81
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{-(-1.1)-\sqrt{0.81}}{2*0.1}=\frac{1.1-\sqrt{0.81}}{0.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.1)+\sqrt{0.81}}{2*0.1}=\frac{1.1+\sqrt{0.81}}{0.2}
$