Question

Which term of the AP : 121, 117, 113,..., is the first negative term ?

[Hint: Find n for a, < 0]​

Answer 1

            ༒ Qυєѕтiσи ༒

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Which term of the AP : 121, 117, 113,..., is the first negative term ?

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            ★彡 Sσℓυтiσи 彡★

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Given :-

• A.P : 121, 117, 113,.....
• a = 121
• d = a2 - a1 = 117 - 121 = -4

Let the n th term be the first negative term of the given G.P.

Then, a n < 0

⟹ an = a + (n - 1) d < 0

⟹ 121 + (n - 1) (-4) < 0

⟹ 121 - 4n + 4 < 0

⟹ 125 - 4n < 0

⟹ -4n < -125

⟹ 4n > 125

⟹ n > 125/4

⟹ n > 31.25

.°. When n = 32, the term becomes negative .

(or)

32nd term is the first negative term of the given A.P.

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