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Find the 20th term of the arithmetic sequence 17, 13, 9,...

Sagot :

Answer:

20th term = [tex]-59[/tex]

Step-by-step explanation:

An arithmetic sequence has the formula

[tex]a_n = a_1 + d(n - 1)[/tex]

where
[tex]a_n $ is the nth term\\a_1 = $ first term\\d = common difference[/tex]

Given the sequence 17, 13, 9, ... we see
[tex]a_1 = 17\\d = -4[/tex]

and we are asked to find the 20th term so n = 20

Using the formula:
[tex]a_{20} = 17 + (-4)(20-1)\\\\a_{20} = 17 + - 4 (19)\\\\a_{20} = 17 - 76\\\\a_{20} = -59[/tex]