2400=20x-(2000+8x+0.0025x^2)

Solution for 2400=20x-(2000+8x+0.0025x^2) equation:

2400=20x-(2000+8x+0.0025x^2)

We move all terms to the left:

2400-(20x-(2000+8x+0.0025x^2))=0


We calculate terms in parentheses: -(20x-(2000+8x+0.0025x^2)), so:

20x-(2000+8x+0.0025x^2)

determiningTheFunctionDomain
-(2000+8x+0.0025x^2)+20x

We get rid of parentheses

-0.0025x^2-8x+20x-2000

We add all the numbers together, and all the variables

-0.0025x^2+12x-2000

Back to the equation:

-(-0.0025x^2+12x-2000)


We get rid of parentheses

0.0025x^2-12x+2000+2400=0

We add all the numbers together, and all the variables

0.0025x^2-12x+4400=0

a = 0.0025; b = -12; c = +4400;
Δ = b2-4ac
Δ = -122-4·0.0025·4400
Δ = 100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{100}=10$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-10}{2*0.0025}=\frac{2}{0.005}
=400
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+10}{2*0.0025}=\frac{22}{0.005}
=4400
$