Question

Find the sum of the First 14 terms of an arithmetic series with a1 =42 and a14=146

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Answer 1

S₁₄ = 1316

Explanation:

given the first and last terms of an arithmetic series then the sum to n terms is

`S_(n)` =
`(n)/(2)` ( first term + last term )

here first term a₁ = 42 and last term a₁₄ = 146 , then

S₁₄ =
`(14)/(2)` (42 + 146) = 7 × 188 = 1316