5=0.1x^2+1.1x+3

Solution for 5=0.1x^2+1.1x+3 equation:

5=0.1x^2+1.1x+3

We move all terms to the left:

5-(0.1x^2+1.1x+3)=0

We get rid of parentheses

-0.1x^2-1.1x-3+5=0

We add all the numbers together, and all the variables

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

a = -0.1; b = -1.1; c = +2;
Δ = b2-4ac
Δ = -1.12-4·(-0.1)·2
Δ = 2.01
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{2.01}}{2*-0.1}=\frac{1.1-\sqrt{2.01}}{-0.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.1)+\sqrt{2.01}}{2*-0.1}=\frac{1.1+\sqrt{2.01}}{-0.2}
$