0.1x^2+0.9x=2.2

Solution for 0.1x^2+0.9x=2.2 equation:

0.1x^2+0.9x=2.2

We move all terms to the left:

0.1x^2+0.9x-(2.2)=0

We add all the numbers together, and all the variables

0.1x^2+0.9x-2.2=0

a = 0.1; b = 0.9; c = -2.2;
Δ = b2-4ac
Δ = 0.92-4·0.1·(-2.2)
Δ = 1.69
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{-(0.9)-\sqrt{1.69}}{2*0.1}=\frac{-0.9-\sqrt{1.69}}{0.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.9)+\sqrt{1.69}}{2*0.1}=\frac{-0.9+\sqrt{1.69}}{0.2}
$