Step-by-Step Step-by-step explanation:
3rd term (a3) = -6
12th term (a12) = -3
We know, nth term of an AP = a1 + (n - 1)d, where d = common difference
a3 = a + (3-1)d = a + 2d = -6...(I)
a12 = a + (12-1)d = a + 11d = -3..(II)
Subtracting (II) from (I), we have
2d - 11d = -6 + 3
=> -9d = -3
=> d = 1/3
Therefore, a + 2×1/3 = -6
=> a + 2/3 = -6
=> a = -6-2/3 = -20/3
Therefore, 18th term
= a + (18-1)d
= -20/3 + 17/3
= -3/3
= -1
Answer:
-1
Hope it helps.
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