Expert: Paul Klarreich - 7/10/2007

Question
Can you solve the following equation for r so i can use it in a formula?

y = 4ar^2 + (4/3)ar^3

Answer
Questioner:   Peter
Category:  Advanced Math
Private:  No
 
Subject:  algebra help
Question:  Can you solve the following equation for r so i can use it in a formula?

y = 4ar^2 + (4/3)ar^3
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Hi, Peter,

Good news:  I can read the question now that we have those special unreadable characters out of it.

Bad news: This is a cubic equation in r, assuming you have it typed correctly.  There isn't any general and simple way to solve this equation for r.  Factoring it:

y = 4ar^2(1 + r/3)

doesn't help much, either.  Sorry.

But is this part of some larger problem?  Perhaps you have decided that the only way to do that other problem is to solve this for r.  You might be wrong about that.  Consider sending that problem in.  Maybe we can work around this issue.