indicated sum of S9:2,16,128​

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Answer:

We think you wrote:

2,-16,128,-1024

This deals with geometric series.

Step-by-step explanation:

Step by Step Solution

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2,-16,128,-1024

Your input appears to be an geometric series.

Find the ratio (r) between adjacent members

a2/a1=-16/2=-8

a3/a2=128/-16=-8

a4/a3=-1024/128=-8

The ration (r) between every two adjacent members of the series is constant and equal to -8

General Form: a

n

=a

1

×r

n-1

This geometric series: a

n

=2×-8

n-1

The nature of this series

Sum of finite geometric series members

sum of a geometric series

The sum of our particular series

a 1-rn = 2 1--84 = 2 1-4096 = 2 -4095 =2×-455=-910

1-r 1--8 9 9

Finding the n

th

element

a2 =a1×r2-1 =a1×r1 =2×-81 =-16

a3 =a1×r3-1 =a1×r2 =2×-82 =128

a4 =a1×r4-1 =a1×r3 =2×-83 =-1024

a5 =a1×r5-1 =a1×r4 =2×-84 =8192

a6 =a1×r6-1 =a1×r5 =2×-85 =-65536

a7 =a1×r7-1 =a1×r6 =2×-86 =524288

a8 =a1×r8-1 =a1×r7 =2×-87 =-4194304

a9 =a1×r9-1 =a1×r8 =2×-88 =33554432

a10 =a1×r10-1 =a1×r9 =2×-89 =-268435456

a11 =a1×r11-1 =a1×r10 =2×-810 =2147483648

a12 =a1×r12-1 =a1×r11 =2×-811 =-17179869184

a13 =a1×r13-1 =a1×r12 =2×-812 =137438953472

a14 =a1×r14-1 =a1×r13 =2×-813 =-1099511627776

l hope it's help