Question

find the value of a1 for an infinite geometric series with S=-45 and r=-1/9.....i get -5 but its saying its wrong. idk how

Answer 1

let a = first term

S = a/(1-r)

-45 = a/(1-(-1/9))

-45 = a/(1+1/9)

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...
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a = ???

Answer 2

.....4?

Answer 3

oh wait

Answer 4

let a = first term

S = a/(1-r)

-45 = a/(1-(-1/9))

-45 = a/(1+1/9)

-45 = a/(9/9+1/9)

-45 = a/(10/9)

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...
...

a = ???

Answer 5

50

Answer 6

-50

Answer 7

let a = first term

S = a/(1-r)

-45 = a/(1-(-1/9))

-45 = a/(1+1/9)

-45 = a/(9/9+1/9)

-45 = a/(10/9)

-45 = 9a/10

-45*10 = 9a

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...
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a = ???

Answer 8

i still get -50...

Answer 9

good, wanted to make sure you weren't just guessing