Sums/Series, basic algebra ?

  • Thread starter kuahji
  • Start date
  • #1
394
2
[tex]\sum[/tex] (2^(2n)-(-7)^n)/(11^n)

The book has that expression equal to
[tex]\sum[/tex] (4/11)^n - [tex]\sum[/tex] (-7/11)^n

I'm not seeing how the first part changes to (4/11)^n. Wouldn't it be (2^2+2^n) & not 4^n? Or is there something else I'm missing?
 

Answers and Replies

  • #2
nicksauce
Science Advisor
Homework Helper
1,272
5
Fact:
[tex](x^y)^z = x^{yz}[/tex].
Does that help you out?
 
  • #3
394
2
Crude, nm. 2am & math doesn't mix sometimes. ^_^
 

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