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Find the nth term of the following sequence 29,
25, 21, 17, 13, ... Then find the 25th term. |
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Solve |
Step |
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d = 13 - 17 = -4,
d = 17 - 21 = -4 |
Find
the common difference. d = -4 |
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an = a1 + (n - 1)d |
Use the formula for arithmetic sequence since there is a common difference. |
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a1 = 29 and d = -4 |
a1 = 29 is the first term of the sequence. |
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an = 29 + (n - 1)(-4) |
Plug in the values and simplify. |
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an = 29 - 4n + 4 = -4n + 33 |
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an = -4n + 33 |
nth term |
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a50 = -4(50) + 33 = -200 + 33 = -167 |
50th term |
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Spot Check |
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a1 = -4(1) + 33 = -4 + 33 = 29 |
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a3 = -4(3) + 33 = -12 + 33 = 21 |
| a5 = -4(5) + 33 = -20 + 33 = 13 |