Geometric Progression
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Geometric Progression

[From: ] [author: ] [Date: 11-09-18] [Hit: ]
?a(2^7) - a(2^5) = 4 so (2^5)(4a-a) = 4 means 3a = 1/8 or a = 1/24.......
Help me, can u tech me how to solve this question

In a geometric sequence, the 8th term exceeds the 6th term by 4. Find the first term if the common ratio is 2, the answer is 3.

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Aiman, Have you really studued G. P.?
a(2^7) - a(2^5) = 4 so (2^5)(4a-a) = 4 means 3a = 1/8 or a = 1/24.

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a6+4=a8
ar^5+4=ar^7 as an=ar^(n-1)
or
2^5a+4=2^7a
32a+4=128a
4=128a-32a
4=96a
a=4/96
a=1/24

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T6 + 4 = T8
a(2)^5 + 4 = a(2)^7
32a + 4 = 128a
96a = 4
a = 1/24 (not 3)
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keywords: Progression,Geometric,Geometric Progression
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