Question

1.Find the 13th partial sum of ( see drawing)
a 118
b 708
c 1,534
d 767

Answer 1

ok this is
\[\sum_{i=1}^{\infty}9i-4\] right?

Answer 2

there is not a chance in hell this converges, because \(9>1\) and so this gets larger and larger. we can however find the partial sums

Answer 3

you are asked for
\[\sum_{i=1}^{13}9i-4\] right? that is the 13th partial sum

Answer 4

I am not really sure, I just know I have to find the 13th partial sum of that sigma notation and i have no clue how to find partial um

Answer 5

and there are a couple of different ways to compute it. someone else might have a snappy way, but i use this
\[\sum_{i=1}^ni=\frac{n(n+1)}{2}\]

Answer 6

ok lets go slow
first of all is it clear what
\[\sum_{i=11}^{13}9i-4\] means?

Answer 7

What is \[\sum_{i=1}^ni=\frac{n(n+1)}{2}\] woudl you mind drawing it out for me?

Answer 8

\[\sum_{i=1}^{13}9i-4\]means add, starting with \(i=1\) then \(i=2\) etc until you get up to \(i=13\)

Answer 9

ohh, okay

Answer 10

Satellite's correct, the 13th partial sum is just taking n from 1 to 13. So you're just summing the first 13 values of the sequence.