Which term of the AP : 3, 8, 13, 18, ......., is 78 ?

Question

KnowledgeBoat · Accepted Answer

In above A.P., 3, 8, 13, 18, ....... First term (a) = 3 Common difference (d) = 8 - 3 = 5. Let nth term of the A.P. be 78. By formula, ⇒ a_n = a + (n - 1)d Substituting values we get : ⇒ 78 = 3 + (n - 1) × 5 ⇒ 78 = 3 + 5n - 5 ⇒ 78 = 5n - 2 ⇒ 5n = 78 + 2 ⇒ 5n = 80 ⇒ n = ⇒ n = 16. Hence, 16th term of the A.P. is 78.

Mathematics

Which term of the AP : 3, 8, 13, 18, ……., is 78 ?

AP

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