Question

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

3 - 15 + 75 - 375 + ...

Answer 1

geez, no one ever posts an easy one ?

Answer 2

@Luis_Rivera @helpmepleas239843 it has to be in summation notation form

Answer 3

sorry that was incorrect one moment

Answer 4

@helpmeplease239843 has this one

Answer 5

\[\Sigma \] on the bottom would be 1 on the top would be the infinite symbol on the right.....

Answer 6

@helpmeplease239843 on the answer choices, each one say on the bottom is n=0

Answer 7

oh on the right would be \[3(-5)^{n-1} \] I think is that an option

Answer 8

How did you get that

Answer 9

the formula for the right is \[a _{n}=a _{1}r ^{n-1}\]
\[a _{1}=3\] r=second number/first number so r=-15/3 or -5
then simply plug in the values

Answer 10

I'm learning the same thing as you right now

Answer 11

thanks for your help

Answer 12

no problem