Question

Please help. Medal?
What is the sum of a 6–term geometric series if the first term is 6 and the last term is 966,306?

Answer 1

@ganeshie8 @jdoe0001 @cwrw238 can any of you help?

Answer 2

@nincompoop @nphuongsun93 please help me with this somebody.

Answer 3

first find the common ration
awe know the first and last terms so

ar^5 / a = r^5 = 966,306 / 6 = 161051

now you need the 5th root of 161051

can u use your calculator to find this?

Answer 4

how would i plug that into my caculator?

Answer 5

161,051 ^ 0.2

Answer 6

got it?

Answer 7

it came out to 11

Answer 8

then use the formula for sum of n terms


Sn = a1 * r^n - 1
--------
r - 1

where a1 = first term and r = common ration

Answer 9

11 is correct

Answer 10

so sum 6 terem = 6 * (11^6 - 1)
--------
11 - 1

Answer 11

10629360?

Answer 12

no - I think you've missed out the last division by 10

Answer 13

right?

Answer 14

oh oops so it would be 1062936?

Answer 15

that's close - I made a slight mistake in the last formula
6 * (11^6 - 1)
------------
11 - 1

isn't correct - the parentheses should not be there
correct is

6 * 11^6 - 1
---------
11 - 1

That works out to 10629366 - 1
------------ = 1062936.5
10

Answer 16

Ok thank you!