Long series and sequence questions (1 Viewer)

[bos1234]

Please full working

 

[LoneShadow]

If the series starts with zeroth term or 1st term, in either case the formula given is incorrect for nth term. Unless I made a blunder.

 

[-pari-]

can you put up what the answers are meant to be?

so i knw whether i got it right or not....

 

[ngogiathuan]

so shame that I don't know how to type mathematical formula here
Well if you can read my typing...I hope I got it right
at n=0
It becomes 2*(3^(-2))-5*0+2
at n=1
2*(3^(-1))-5*1+2
at n=2
2*(3^(0)-5*2+2
...
Generalising
The total sum is 2* (3^(-2)+3^(-1)+3^0...+3^6) +5 (0 + 1 +2 +...8)+16
In the first bracket it is a geometric serie
In the second one is a arithmetic serie