**Nevermind, I found the error while editing this post! Good thing I shared this, sorry for the forum clutter! I don't know how to delete the thread.**
Hi, I have a problem that looks like this:

(1)

L = 28490

D = 2183

Solve for B.

The solution gives B = 622

Values may have been rounded at various steps during their derivation, so some error of around 10-30 may occur.

This formula is derived from the notes and used to solve a problem from the professor. The (+-) indicates that in the notes, a minus(-) sign is used, while in the professor's solution set, he uses a plus(+). When I plug in the correct numbers using the solution, it seems a minus (-) is correct; however, in solving for B, I have to square both sides, so I don't see how the plus/minus (+-) should matter. This confuses me that when I work the problem backwards using B to solve for L, the minus is important, but when I solve for B, I cannot for the world of me see its relevance.

Here's my work:

(1)

(2)

(3)

(4)

(5)