Question

Find the 11th partial sum of..

Answer 1

I didn't know how to write the equation out on here!

Answer 2

add up the first 11 terms ...

Answer 3

you can either brute math it, or use summation properties.

Answer 4

-7(1) + 22
-7(2) + 22
-7(3) + 22
. . .
-7(11) + 22
------------------------
-7(1+2+3+...+11) + 22(11)

all thats really 'hard' is knowing the sum of the digits from 1 to 11

Answer 5

its simple enough to find 2times the sum, by adding it in a useful way:

1 + 2 + 3 + ... + 11
11 + 10 + 9 + ... + 1
--------------------
12 + 12 + 12+ ... + 12

so we should be able to discern that the sum of 1 to 11 is equal to half of 11(12)

Answer 6

\[11\left(-\frac{7(12)}{2}+22\right)\]
i wonder if that can be remembered as a formula .. prolly not

Answer 7

-220! Thanks :)

Answer 8

youre welcome :)