Question

HELP PLEASE 1 MEDAL
What is the sum of the geometric sequence -1,6,-36... if there are 7 terms.?

Answer 1

have you found a pattern so far?

Answer 2

that's critical to answering this.

Answer 3

*6?

Answer 4

is that your answer or is there really 6 terms?

Answer 5

no theres 7

Answer 6

ok. So have you found a pattern?

Answer 7

i thought it was * 6

Answer 8

you're very close, but not quite there yet. look at the first given number : "-1". that times 6 is what?

Answer 9

6 so its -6?

Answer 10

is -6 the second given number?

Answer 11

no.

Answer 12

ok, so your pattern must be off somehow. how is -6 different than 6?

Answer 13

it's not

Answer 14

wait its positive haha

Answer 15

there ya go. so, if the second number is -6 times the previous number, then perhaps that's the rule. see if the third number is -6 times the second given number.

Answer 16

yes it is so i just keep on multiplying times 6 right?

Answer 17

not by 6.

Answer 18

what'd you find the pattern to be?

Answer 19

6,665 would be the 7th term?