- #1

air-man001

- 9

- 0

**Please please, I need solution**

hello every one

I have this summation in my book

infinity

[tex]\sum[/tex] k*z

^{-k}

k=0

my solution:

infinity

[tex]\sum[/tex] k*z

^{-k}= z

^{-1}+2z

^{-2}+3z

^{-3}+............

k=0

please i want the closed form (step-by-step)

Last edited: