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The first term of an A.P. is 5, the last term is 45 and sum is 400. Find the number of terms and the common difference. |
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Answer» `" "a = 5` `" "a_n = 45` `" "S_n = 400` `rArr (n)/(2) (5+ 45) = 400` `50 n = 800` `n = 16` also `a_n = 45` `5 + 15 d = 45` ` 15 d = 40` `d= 8//3` |
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