Question

Find the sum of 12 terms of ap when nth term is 3n+4

Answer 1

Answer:

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Explanation:

Answer:-

Given:

nth term of an AP (a(n)) = 3n + 4.

Put the value of n as 1 to find the first term.

→ a(1) = 3(1) + 4

→ a = 7

Now 12th term (a(12)) = 3(12) + 4

→ a(12) = 40

We know that,

Sum of first n terms of an AP = n/2( a + l) where "l" is the last term

→ Sum of first twelve terms = 12/2(7 + t(12))

→ S(12) = 6(7 + 40)

→ S(12) = 6(47)

→ S(12) = 282

Hence, the sum of first twelve terms of the given AP is 282.

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