# A^3 / (A -2) = B Could someone solve this for 'A' ?

• Aug 8th 2011, 01:42 PM
wolf
A^3 / (A -2) = B Could someone solve this for 'A' ?
If B= A^3 / (A -2) what does 'A' equal?
• Aug 8th 2011, 01:54 PM
Siron
Re: A^3 / (A -2) = B Could someone solve this for 'A' ?
Do you want an expression like: $A=...$ so in function of B?
• Aug 8th 2011, 02:11 PM
wolf
Re: A^3 / (A -2) = B Could someone solve this for 'A' ?
Yes, I would like the equation solved in terms of A.
For example, if 2A^2 = B, then A = square root (B/2)
• Aug 8th 2011, 02:40 PM
Siron
Re: A^3 / (A -2) = B Could someone solve this for 'A' ?
My first impression says it's not possible.
• Aug 8th 2011, 02:51 PM
Plato
Re: A^3 / (A -2) = B Could someone solve this for 'A' ?
Quote:

Originally Posted by wolf
Yes, I would like the equation solved in terms of A.
For example, if 2A^2 = B, then A = square root (B/2)

There are some conditions under which a cubic can be solved.
Here is a discussion.
• Aug 8th 2011, 02:53 PM
Quacky
Re: A^3 / (A -2) = B Could someone solve this for 'A' ?
Possible, but not fun, according to my cheating. It depends on why you'd need it.
• Aug 8th 2011, 02:54 PM
Siron
Re: A^3 / (A -2) = B Could someone solve this for 'A' ?
Quote:

Originally Posted by Quacky
Possible, but not fun, according to my cheating. It depends on why you'd need it.

That's indeed not really fun to do :).
• Aug 8th 2011, 04:09 PM
wolf
Re: A^3 / (A -2) = B Could someone solve this for 'A' ?
Thank you Siron, Plato and especially Quacky for the link to the answer.
At first that seems as if it's an easy equation to solve but not after looking at that answer.
Thanks everyone.
• Aug 9th 2011, 03:35 AM
Bacterius
Re: A^3 / (A -2) = B Could someone solve this for 'A' ?
Yes polynomials do tend to "look" easy to solve because they have nice round integers as coefficients... but in general solving a polynomial algebraically is not easy. For instance solving $x^5 - 1 = 0$ is easy, make that $x^5 + 2x - 1 = 0$ and we're all stumped. In fact in practice polynomials are solved by approximation in the real world. But that doesn't mean it's wrong to learn how to solve cubics!