the sum of 8th & 17th term of an AP is 36 find the sum of first terms of the AP
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Sum of first ( how many terms
24
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this is correct but this is incomplete so not able to do the other steps
pls resend the question correctly
pls resend the question correctly
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T8 =a+(8-1)d
T8=a+7d
Similarly
T17 = a+16d
T8+T17 =36 (given)
Substitute the above values
(a+7d) + (a+16d) =36
2a + 23d =36.......eq 1
Sn=n/2(2a+(n-1)d)
S24 = 24/2(2a + (24-1)d)
S24 = 12(2a +23d)
From eq 1 that is 2a +23d =36 substitute
S24 = 12 × 36
S24 = 432
T8=a+7d
Similarly
T17 = a+16d
T8+T17 =36 (given)
Substitute the above values
(a+7d) + (a+16d) =36
2a + 23d =36.......eq 1
Sn=n/2(2a+(n-1)d)
S24 = 24/2(2a + (24-1)d)
S24 = 12(2a +23d)
From eq 1 that is 2a +23d =36 substitute
S24 = 12 × 36
S24 = 432
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