Question

Write the sum using summation notation, assuming the suggested pattern continues.

-9 - 3 + 3 + 9 + ... + 81

Answer 1

@hartnn what about this

Answer 2

what would you multiply to current term to get next term ?

Answer 3

add 6?

Answer 4

multiply/add/divide/subtract**

Answer 5

ok

Answer 6

summation of the quantity negative nine plus six n from n equals zero to fifteen
summation of negative fifty four times n from n equals zero to fifteen
summation of negative fifty four times n from n equals zero to infinity
summation of the quantity negative nine plus six n from n equals zero to infinity

Answer 7

those are the choices

Answer 8

ik we can cross out the last 2 because they are infinity and this one ends with 81

Answer 9

yes, adding 6 is correct,
so this is indeed an arithmetic series,
lets find the n'th term equation for that

\(a_n = a_1 +(n-1)d\)

we know d - common difference = 6
a1 = 1st term = -9
plug in!

Answer 10

and you're right! this is a finite series,
the answer is from 1st 2 choices only :)

Answer 11

-9+6(n-1)

Answer 12

so it would be the first choice?

Answer 13

yes, thats correct :)

Answer 14

thank you again!

Answer 15

welcome ^_^