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प्रश्न
If 8th term of an A.P. is zero, prove that its 38th term is triple of its 18th term.
उत्तर
T8 = 0
To prove that T38 = 3 x T18
Let a be the first term and d be the common difference
∴ T8 = a + 7d = 0
⇒ a = –7d
Now
T38 = a + 37d
= –7d + 37d
= 30d
and
T18 = a + 17d
= –7d + 17d
= 10d
It is clear that T38 is triple of T18.
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