Find the difference of the arithmetic progression, the first term of which is 12 and the eighth term is -9.
| April 29, 2021 | education
To solve the problem, we use the formula for the nth term of the arithmetic progression.
an = a1 + d * (n – 1), where a1 is the first term of the progression, n is the difference of the arithmetic progression, n is the ordinal number of the member of the arithmetic progression.
a8 = a1 + d * (8 – 1).
-9 = 12 + d * 7.
7 * d = -21.
d = -21 / 7 = -3.
Answer: The difference of the arithmetic progression is -3.
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