-.04x^2+2.1x+6.1=0

Solution for -.04x^2+2.1x+6.1=0 equation:

-.04x^2+2.1x+6.1=0

We add all the numbers together, and all the variables

-0.04x^2+2.1x+6.1=0

a = -0.04; b = 2.1; c = +6.1;
Δ = b2-4ac
Δ = 2.12-4·(-0.04)·6.1
Δ = 5.386
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{-(2.1)-\sqrt{5.386}}{2*-0.04}=\frac{-2.1-\sqrt{5.386}}{-0.08}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2.1)+\sqrt{5.386}}{2*-0.04}=\frac{-2.1+\sqrt{5.386}}{-0.08}
$