Math, asked by farooq51, 1 year ago

the sum of first 8terms of an ap is 100 and sum of first 19 terms is 551.find ap

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Answered by YasminGautam

sum of n terms in AP can be given by (n/2)*[2a+(n-1)d]

sum of first 8 terms = 4*[2a+7d] =100

or 2a+7d = 25 (1)

sum of first 19 terms = (19/2)*[2a+18d] =551

or 2a+18d = 58 (2)

subtracting (2) - (1), we get

11d =33

d =3

2a+7*3= 25

a =2

hence the AP is 2,5,8,11...

farooq51: how can i send you the question paper

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YasminGautam: start typing your question .....and then click ask question option ..... after that on you left side y'll see an icon for taking pictures...just click that

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Answered by New57

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the sum of first 8terms of an ap is 100 and sum of first 19 terms is 551.find ap​

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the sum of first 8terms of an ap is 100 and sum of first 19 terms is 551.find ap