0=-0.09d^2+0.9d+2

Solution for 0=-0.09d^2+0.9d+2 equation:

0=-0.09d^2+0.9d+2

We move all terms to the left:

0-(-0.09d^2+0.9d+2)=0

We add all the numbers together, and all the variables

-(-0.09d^2+0.9d+2)=0

We get rid of parentheses

0.09d^2-0.9d-2=0

a = 0.09; b = -0.9; c = -2;
Δ = b2-4ac
Δ = -0.92-4·0.09·(-2)
Δ = 1.53
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-0.9)-\sqrt{1.53}}{2*0.09}=\frac{0.9-\sqrt{1.53}}{0.18}
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.9)+\sqrt{1.53}}{2*0.09}=\frac{0.9+\sqrt{1.53}}{0.18}
$