Mathematics
Which term of the AP : 121, 117, 113,……, is its first negative term?
AP
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Answer
In the above A.P.,
First term (a) = 121 and common difference (d) = 117 - 121 = -4.
Let nth term be the first negative term.
So,
⇒ an < 0
⇒ a + (n - 1)d < 0
⇒ 121 + (n - 1)(-4) < 0
⇒ 121 - 4n + 4 < 0
⇒ 125 - 4n < 0
⇒ 4n > 125
⇒ n >
⇒ n >
⇒ n = 32.
Hence, 32nd term is the first negative term.
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