Question

The sum of the first 15 terms of an
AP is 495 its 5th term 21.
a) Find the its 8th term​

Answer 1

Answer:

i dont know the answer

Step-by-step explanation:

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Answer 2

Answer:

Sn = (n/2)[2a + (n-1)d]

Tn = a + (n – 1)d

S15 = (15/2)(2a + 14d) = 495

Or S15 = 15a + 105d = 495 …. (1)

T5 = a + 4d = 21 …. (2)

From (2), substitute a = 21 – 4d in (1) to get

45d = 180

So d = 4

And a = 21 – 4(4) = 5

So T8 = 5 + 7(4) = 33