28000=x(1-1.005^-156/0.005)

Solution for 28000=x(1-1.005^-156/0.005) equation:

28000=x(1-1.005^-156/0.005)

We move all terms to the left:

28000-(x(1-1.005^-156/0.005))=0

We multiply all the terms by the denominator


-(x(1-1.005^-156+28000*0.005))=0


We calculate terms in parentheses: -(x(1-1.005^-156+28000*0.005)), so:

x(1-1.005^-156+28000*0.005)

We multiply parentheses

-1x^2+x-156x+140x

We add all the numbers together, and all the variables

-1x^2-15x

Back to the equation:

-(-1x^2-15x)


We get rid of parentheses

1x^2+15x=0

We add all the numbers together, and all the variables

x^2+15x=0

a = 1; b = 15; c = 0;
Δ = b2-4ac
Δ = 152-4·1·0
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-15}{2*1}=\frac{-30}{2}
=-15
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+15}{2*1}=\frac{0}{2}
=0
$