2 years ago

Please help me if i dont do this now then im loosing my phone .

Mathematics

1 answer:

AURORKA [14]2 years ago

6 0

I feel sorry for you if this is too hard

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Elenna [48]

48 i believe thats the best i can find

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3 years ago

Read 2 more answers

Use the formula to evaluate the series 1/4 + 1/9 + 1/27 + 1/81.

Dmitriy789 [7]

Is the first term supposed to be 1/4, or did you actually mean 1/3?

I'll assume the latter. Write

$S=\dfrac13+\dfrac19+\dfrac1{27}+\dfrac1{81}$
$S=\dfrac13+\dfrac1{3^2}+\dfrac1{3^3}+\dfrac1{3^4}$
$\dfrac13S=\dfrac1{3^2}+\dfrac1{3^3}+\dfrac1{3^4}+\dfrac1{3^5}$
$\implies S-\dfrac13S=\dfrac13-\dfrac1{3^5}$
$\dfrac23S=\dfrac13\left(1-\dfrac1{3^4}\right)$
$S=\dfrac12\left(1-\dfrac1{81}\right)$
$S=\dfrac{40}{81}$