Foundation
Mathematics Foundation
nth term of AP
Question
Which term of the AP, 25, 20, 15, ..... is the first negative term ?
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Solution
Let Tn < 0. Then, 25 + (n – 1) × (– 5) < 0.
30 < 5n ⇒ 5n > 30 ⇒ n > 6.
So, the required term is 7th.