2+1.1x-0.1x^2=4

Solution for 2+1.1x-0.1x^2=4 equation:

2+1.1x-0.1x^2=4

We move all terms to the left:

2+1.1x-0.1x^2-(4)=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 = 0.41
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{0.41}}{2*-0.1}=\frac{-1.1-\sqrt{0.41}}{-0.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.1)+\sqrt{0.41}}{2*-0.1}=\frac{-1.1+\sqrt{0.41}}{-0.2}
$