0=-0.06x^2-0.9x+2.1

Solution for 0=-0.06x^2-0.9x+2.1 equation:

0=-0.06x^2-0.9x+2.1

We move all terms to the left:

0-(-0.06x^2-0.9x+2.1)=0

We add all the numbers together, and all the variables

-(-0.06x^2-0.9x+2.1)=0

We get rid of parentheses

0.06x^2+0.9x-2.1=0

a = 0.06; b = 0.9; c = -2.1;
Δ = b2-4ac
Δ = 0.92-4·0.06·(-2.1)
Δ = 1.314
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{1.314}}{2*0.06}=\frac{-0.9-\sqrt{1.314}}{0.12}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.9)+\sqrt{1.314}}{2*0.06}=\frac{-0.9+\sqrt{1.314}}{0.12}
$