Question

find the values of the terms a and b so that a,7,b,23,31,... is an AP ​

Answer 1

a,7,b, 23,31 are in AP . . . . . . . .. . (given )
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Therefore it's common difference must be constant.
. Common difference =31-23 =8
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Therefore,
7-a should also be =8
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7-a=8
a=7-8
a = -1

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23-b =8
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b=23-8
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b= 15

ANS: a= -1 , b = 15
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Hope you have no doubts.