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Mathematics 14 Online
OpenStudy (eskelle):

What is S10 for 1+3+9+27?

OpenStudy (eskelle):

i think that it is timesd by three. the options are a. 9,841 b. 29,525 c. 14,762 d. 29,524

Vocaloid (vocaloid):

an = a1 * r^(n-1) where r = common ratio and a1 = first term

Vocaloid (vocaloid):

and n = 10

Vocaloid (vocaloid):

let me know what you get

OpenStudy (eskelle):

what is the common ratio? 3?

Vocaloid (vocaloid):

yes

OpenStudy (eskelle):

ok

Vocaloid (vocaloid):

oh wait

Vocaloid (vocaloid):

just a moment

Vocaloid (vocaloid):

wrong formula

Vocaloid (vocaloid):

this one should work https://www.mathsisfun.com/algebra/images/partial-sum-i.gif

OpenStudy (eskelle):

oh ok

OpenStudy (eskelle):

i dont really get it

Vocaloid (vocaloid):

a = 1 r = 3 n = 10 plug these into the formula and solve

OpenStudy (eskelle):

what is the big e thing?

Vocaloid (vocaloid):

that's sigma

Vocaloid (vocaloid):

just pay attention to this part:

Vocaloid (vocaloid):

Vocaloid (vocaloid):

sigma (the E thing) just means this is a sum formula

OpenStudy (eskelle):

1(1-3^10/1-3)

Vocaloid (vocaloid):

yes but what does that equal?

OpenStudy (eskelle):

29525.5

Vocaloid (vocaloid):

good! (that extra .5 is probably rounding error) so 29,525 is your answer

OpenStudy (eskelle):

okay thank you

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