Question

The 8th term of arithmetic sequence is 67 and 18th term is 147.find common difference. Find 25th term. Write down the sequence

Answer 1

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The common difference is (147–67)/(18–8) = 8.

Let a be the first term. We know that the common difference d = 8. The nth term = a + (n-1)d = a + 8(n-1).

The 8th term is 67, so 67 = a + 8(8–1). Solving yields a=11. (Double check: The 18th term would be 11 + 8(18–1) = 11 + 136 = 147, which is correct.

The nth term is 11 + 8(n-1), so the 25th term is 11 + 8(25–1) = 203.