Question

answer with explanation
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Answer 1

Assuming
K + 9 , 2k - 1 , 2k + 7 are in A.P
then
2k - 1 - k - 9 = 2k + 7 - 2k + 1 (If a,b,c are in
A.P then b- a = c - b = common difference)
So
K - 10 = 8
K = 18
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Answer 2

Answer:

Let,

k + 9 = a

2k - 1 = b

2k + 7 = c

To be in AP,

a + c = 2b

(k + 9) + (2k + 7) = 2(2k - 1)

k + 9 + 2k + 7 = 4k - 2

3k + 16 = 4k - 2

3k - 4k = - 2 - 16

 - k = - 18

k = 18

For k = 18, the terms k+9 , 2k - 1 , 2k + 7 are in AP

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