Question:
The 7th term of an AP is −4 and its 13th term is −6. Find the AP.
Solution:
Thus, first term = 8 and common difference = -2
∴ The terms of the AP are 8, 6, 4, 2,...
We have:
T7 = a + (n - 1)d
⇒ a + 6d = -4 ...(1)
T13 = a + (n - 1)d
⇒ a + 12d = -16 ...(2)
On solving (1) and (2), we get:
a = 8 and d = -2
Thus, first term = 8 and common difference = -2
∴ The terms of the AP are 8, 6, 4, 2,...
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