0=-0.0004x^2+x+2.5

Solution for 0=-0.0004x^2+x+2.5 equation:

0=-0.0004x^2+x+2.5

We move all terms to the left:

0-(-0.0004x^2+x+2.5)=0

We add all the numbers together, and all the variables

-(-0.0004x^2+x+2.5)=0

We get rid of parentheses

0.0004x^2-x-2.5=0

We add all the numbers together, and all the variables

0.0004x^2-1x-2.5=0

a = 0.0004; b = -1; c = -2.5;
Δ = b2-4ac
Δ = -12-4·0.0004·(-2.5)
Δ = 1.004
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)-\sqrt{1.004}}{2*0.0004}=\frac{1-\sqrt{1.004}}{0.0008}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{1.004}}{2*0.0004}=\frac{1+\sqrt{1.004}}{0.0008}
$