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Find 15th term of an arithmetic series is 102 and the 31st term is 160a: find the first term and common difference b: find the 100th term of the series. |
Answer» SOLUTION :(a). A15 = 102 and A31 = 160 a + 14d = 102 --> ( i ) and a + 30d = 160 --> ( ii ) a = 102 - 14d Put it in equation (ii) (102 - 14d) + 30 d = 160 102 + 16D = 160 16d = 58 d = 29/8 First TERM, a = 102 - 14 * 29/8 a = 205/4
(ii) Now, A100 = 205 /4 + 99× 29/8 A 100 = 3281 / 8 |
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