? asked in Science & MathematicsMathematics · 10 years ago

given the first and last term; arethmetic series?

the terms A=3, T6=11.

you need to find the sum of each arthmetic series

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  • 10 years ago
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    Recall that for an arithmetic progression (AP) with initial term a and common difference d, the n-th term is t(n) = a + (n-1) d.

    Here a = 3, n = 6, so

    11 = t(6) = a + (6-1) d = 3 + 5 d, so d = 8/5 = 1.6.

    So t(n) = a(1) + (n-1) d = 3 + 1.6 (n-1) = 1.6 n + 1.4.

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