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Identify the 27th term of an arithmetic sequence where a1 = 38 and a17 = -74.
Solution:
The formula to find the nth term in an arithmetic sequence is
an = a1 + (n - 1)d
Where an = nth term
a1 = first term
n = term position
It is given that
a1 = 38, a17 = -74
an = a1 + (n - 1)d
⇒ -74 = 38 + (17 - 1)d
⇒ -74 = 38 + 16d
⇒ 16d = -74 - 38
⇒ 16d = -112
⇒ d = -7
We know that
⇒ a27 = a1 + (n - 1) d
⇒ a27 = 38 + (27 - 1)(-7)
⇒ a27 = 38 + (26)(-7)
⇒ a27 = 38 - 182
⇒ a27 = -144
Therefore, the 27th term is -144.
Identify the 27th term of an arithmetic sequence where a1 = 38 and a17 = -74.
Summary:
The 27th term of an arithmetic sequence where a1 = 38 and a17 = -74 is -144.
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