Question

Second term in an ap is 8 and the 8th term is 2 more than the thrice the second term find the sum of first 8 terms

Answer 1

hope this helps you

Answer 2

The sum of first 8 terms is 124

Step-by-step explanation:

Second term = $a_2=8$

a+d=8 ---1

We are given that the 8th term is 2 more than the thrice the second term

Formula of nth term = $a_n=a+(n-1)d$

$a_8=a+(8-1)d\\a_8=a+7d$

ATQ

a+7d=2+3(8)

a+7d=2+24

a+7d=26

Using 1

a+7(8-a)=26

a+56-7a=26

30=6a

5=a

Sum of first n terms =$S_n= \frac{n}{2}(2a+(n-1)d)$

$S_8=\frac{8}{2}(2a+7d)\\S_8=4(a+26)\\S_8=4(5+26)\\S_8=124$

Hence the sum of first 8 terms is 124

#Learn more:

If square of the Second term of an apiece equal to it's 12th term 10th term is thrice the third term find sum of first 25 terms of that ap

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