Question

Find the indicated sum.

Answer 1

@amistre64 Need Help Please

Answer 2

yo have 4 numbers to add up

Answer 3

4 1 -1 and 11

Answer 4

\[\large \sum_{k = 1}^{4} (-1)^{k}(k + 11)\]

Plug in 1 then 2 then 3 then 4 into your equation and solve...then add up your results...so for example...with k = 1...you would have

\[\large \sum_{k = 1}^{4} (-1)^{1}(1 + 11)\]
\[\large \sum_{k = 1}^{4} (-1)(12)\]
\[\large -12\]

This would be what this equals when k = 1...now do this again for k = 2, 3 and 4

Answer 5

\[(-1)^1(1+11)+(-1)^2(2+11)+(-1)^3(3+11)+(-1)^4(4+11)\]
\[-(12)+(13)-(14)+(15)\]

Answer 6

1+1 = 2 :/

Answer 7

so 2 or -12 is the answer @amistre64 @johnweldon1993

Answer 8

its a little insulting when people just ask for the answer after such a well defined explanation. What about the process is confusing?

Answer 9

john explained that the first term is -12

i showed all the terms ... the rest is just adding up the terms

Answer 10

no what i mean by the answer os u explained and johnweldon also explained
Which explanation is the correct one ?

Answer 11

They are both the same...I merely did it for the first term...and amistre showed what the full process would be after plugging in each term

Answer 12

so from amistre's explaination...you were given the 4 results...you just need to add them

Answer 13

ohh is it
thnxs @amistre64 and i am sory

Answer 14

'sok ;)

Answer 15

thnxs to @johnweldon1993 thnxs again

Answer 16

No problem!