#836 · Algebra · Sequences & series

Sum of n terms

If the sum of the first 7 terms of an arithmetic progression is 49 and the sum of the first 17 terms is 289, find a formula for the sum of the first $n$ terms.

~4 minAnswer checked instantlyarithmetic progressionsum formula

H. S. Hall & S. R. Knight, Higher Algebra (1891) · Ch. IV. Arithmetical Progression, Examples IV.b, No. 10

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