Math Is Fun Forum

richard clark

Member

Registered: 2009-05-28

Posts: 1

For all you algebra buffs

I need to transpose a formula and my algebra isn't up to it.  I would welcome any suggestions or solutions.  the formula is:

S =  (A * (A + 1) * (A + 2))
       ---------------------------
                    6

I need to rearrange this and make "A" the subject of the formula.  I believe there is a method using sucessive approximations but I would prefer not to take this approacg. If anybody fancies a little bit of brain-bashing, please feel free.

Many thanks

Richard Clark

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: For all you algebra buffs

Algebra won't be enough.  You have the points A = 0, A = -1, and A = -2 all give the value S = 0.  This means the inverse (i.e. solving for A) won't be a function.  You can locally come up with approximations for the inverse where the derivative with respect to A is nonzero, but this is about all you can do.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."