SOLUTION: Please help me with this problem: Resolve into infinite series {{{ax/(a-x)}}} I can't show how I tried on this problem because it is very complicated! I did try several times t

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Question 1116740: Please help me with this problem: Resolve into infinite series ax%2F%28a-x%29
I can't show how I tried on this problem because it is very complicated! I did try several times though.
This is the answer from my key book: x+x^2/a+x^3/a+x^4/a,ect., to infinity
I don't understand how the fractions are able to keep repeating. When I worked the problem I got as far as x+x^2/a, but no farther.
I appreciate any help you can offer!

Found 2 solutions by Edwin McCravy, ikleyn:
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!

It's done by special long division:

       x + x²/a + x³/a² + ∙∙∙ 
a - x)ax
      ax - x²
           x²   - x³/a²
                  x³/a² -    

If you need further explanation, just ask in the note-form
below and I'll get back to you by email.

Edwin

Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.

            The formula in your post is written   I N C O R R E C T L Y.

            The correct formula is   T H I S:

            ax%2F%28a-x%29 = x + x%5E2%2Fa + x%5E3%2Fa%5E2 + x%5E4%2Fa%5E3 +  .  .  .  ,   ect.,   to infinity.

.
It is not difficult to prove it   //   if you know the formula for the sum of an infinite geometric series . . .

a%2F%28a-x%29 = a%2A%281%2F%28a%2A%281-x%2Fa%29%29%29%29 = 1%2F%281-x%2Fa%29.


The very right fraction  1%2F%281-x%2Fa%29  is the sum of an infinite geometric progression with the first term of "1" and the common ratio of x%2Fa:


1%2F%281-x%2Fa%29 =  1 + x%2Fa + x%5E2%2Fa%5E2 + x%5E3%2Fa%5E3 + . . .      (1)


Now multiply both sides of (1) by x, and you will get the required solution


%28ax%29%2F%28a-x%29 = x + x%5E2%2Fa + x%5E3%2Fa%5E2 + x%5E4%2Fa%5E3 + . . .


QED.

Solved.