If the first 7 terms of an ap is 49 and first 17 term of an ap is 289

1.	If the first 7 terms of an ap is 49 and first 17 term of an ap is 289 then find the n
Answer» 7 a7 = a + 6d = 49-------------(1)a17 = a + 16d = 289------------(2)Subtract (1) from (2) ; a + 6d = 49 a + 16d = 289(-) (-) (-) ————————— -10d. = -24010d = 240 : [ d = 24 ] Putting the value of d in (1) ;a + 6d = 49a + 6 × 24 = 49a + 144 = 49a = 49 - 144[ a = -95 ]An is not given in your question otherwise the formula of an is "a+(n-1)d"............ I think your question is incomplete

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