Thread: Power series

I have a problem i cant seem to figure out. I am trying to find the power series expansion for the function


c = 5

Now, would i arrange the 5 + x to force a negative?



then, subtract C? I think this is where i get confused on how to handle C correctly!






But, somehow this isnt correct..

Originally Posted by icelated

I have a problem i cant seem to figure out.


c = 5

Now, would i arrange the 5 + x to force a negative?



then, subtract C? I think this is where i get confused on how to handle C correctly!






But, somehow this int correct..

What is the point?
What is the question?
What are you trying do?

Sorry, i am trying to find the power series expansion for the function

Why 10 - (-x+5) can you show me how to properly add the C? i just dont see how you got 10

Originally Posted by icelated

Why 10 - (-x+5) can you show me how to properly add the C? i just dont see how you got 10

uhh ... 10 - 5 = ?

Sorry, still confused. I thought we are to follow this form (x-c) -c

Originally Posted by icelated

Sorry, still confused. I thought we are to follow this form (x-c) -c

no, you want the form k - (x-c)

in this case, k - [-(x - c)] ... see why k = 10?

Another way to do that is to write

and now divide both numerator and denominator by -5:


If you let that becomes

which is, of course, the sum of the geometric series

Originally Posted by HallsofIvy

Another way to do that is to write

and now divide both numerator and denominator by -5: <--- check this step ...

...

Originally Posted by skeeter

no, you want the form k - (x-c)

in this case, k - [-(x - c)] ... see why k = 10?

I understand the form but we are to subtract c from x and then add c to k ? You seem to be forcing 10. I have not done this in the homework at all.
So, would this be correct 9 / -5 + (x - 5) - 5 ??

Originally Posted by icelated

I understand the form but we are to subtract c from x and then add c to k ? You seem to be forcing 10. I have not done this in the homework at all.
So, would this be correct 9 / -5 + (x - 5) - 5 ??

exactly ... to get the denominator in the desired form to write a power series centered at 5


no, 9/[-5 + (x-5) - 5] = 9/(x - 15)


... probably because you have not come across a problem (like this one) that does not follow a "cook-book" procedure. I recommend you speak w/ your instructor about it.