B^3-13b^2=-40b

Solution for B^3-13b^2=-40b equation:

^3-13B^2=-40B

We move all terms to the left:

^3-13B^2-(-40B)=0

We add all the numbers together, and all the variables

-13B^2-(-40B)=0

We get rid of parentheses

-13B^2+40B=0

a = -13; b = 40; c = 0;
Δ = b2-4ac
Δ = 402-4·(-13)·0
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$B_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$B_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$B_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-40}{2*-13}=\frac{-80}{-26}
=3+1/13
$
$B_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+40}{2*-13}=\frac{0}{-26}
=0
$