Given an arithmetic progression of 14,9,4. Find what number is on the 81st place?

To determine the nth term of the arithmetic progression, we use the formula.

an = a1 + (n – 1) * d, where:

an – n – th member of the progression,

a1 – the first member of the progression,

n is the ordinal number of a member of the progression,

d – the difference of the arithmetic progression.

Then: a31 = a1 + (n – 1) * d = 14 + (31 – 1) * 5 = 14 – 150 = -136.

Answer: The 31st member of the progression is -136.




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