Q9 of 176 Page 8

Find the number of terms of the A.P.

41, 38, 35, ..., 8?

Here, a = 41 , d = 38 – 41 = –3 and l = 8


where l = a + (n – 1)d


⇒ 8 = 41 + (n – 1)(–3)


⇒ 8 = 41 –3n + 3


⇒ 8 = 44 – 3n


⇒ 8 – 44 = –3n


⇒ –36 = –3n



Hence, the number of terms in the given AP is 12


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