Mathematics: Add the first 9 terms of this sequence: -7, -7/2, -7/4, -7/8, -7/16, ...

Add the first 9 terms of this sequence: -7, -7/2,

emm16045

07.09.2021

Sum is -3577/256

Step-by-step explanation:

This is a geometric progression:

$S = \frac{a( 1 - {r}^{n} )}{1 - r } \\ for \: \: r < 1$

S is the sum

a is the first term, a = -7

r is the common ratio, r = -7/2 ÷ -7 = ½

substitute:

$S = \frac{ - 7(1 - {( \frac{1}{2}) }^{9} }{1 - \frac{1}{2} } \\ \\ S = \frac{ - 6.986}{ \frac{1}{2} } \\ \\ S = - \frac{3577}{256}$

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travawnward

21.05.2022

thx

Step-by-step explanation:

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