D=250x*0,997^x-55x

Solution for D=250x*0,997^x-55x equation:

=250D*0.997^D-55D

We move all terms to the left:

-(250D*0.997^D-55D)=0

We get rid of parentheses

-250D*0.997^D+55D=0

We add all the numbers together, and all the variables

55D-250D*0.997^D=0

Wy multiply elements

0D^2+55D=0

We add all the numbers together, and all the variables

D^2+55D=0

a = 1; b = 55; c = 0;
Δ = b2-4ac
Δ = 552-4·1·0
Δ = 3025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$D_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$D_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3025}=55$
$D_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(55)-55}{2*1}=\frac{-110}{2}
=-55
$
$D_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(55)+55}{2*1}=\frac{0}{2}
=0
$