Question

Find the indicated sum.

Answer 1

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

Answer 2

okay I got
-12
13
-14
-15
do I add them together or subtract

Answer 3

how -15 ?

Answer 4

(-1)^4(4+11)

Answer 5

and add them like -12+13+(-14)+15
(-1)^4 = 1

Answer 6

so then it is 2

Answer 7

yup.

Answer 8

that is what i thought it was because of my choices but I just could not get it to add up
my choices are
a. 2
b. 54
c. 46
d. -54
and the only one that made since was 2

Answer 9

thank you

Answer 10

welcome :)