Find the arithmetic sequence.

Question

a) Find the sum of the first 70 terms of the arithmetic sequence: 22, 19, 16, 13, …
b) Find the sum of the first 95 terms of the arithmetic sequence: -17, -12, -7, -2, …
c) Find the sum of the first 777 terms of the arithmetic sequence: 3, 9, 15, 21, …

Answer 1

a) S₇₀ = 35(2(22) + 69(3))

b) S₉₅ = 47.5(2(-17) + 94(5))

c) S₇₇₇ = 388.5(2(3) + 776(6))

 

 

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