Q8 of 178 Page 526

How many terms are there in the AP 41, 38, 35, ..., 8?

In the given AP, the first term = a =41

Common difference = d = 38 - 41 = - 3


Last term = 8


To find: No. of terms in the AP.


Since, we know that


an = a + (n - 1) × d


∴ 8 = 41 + (n - 1) × (-3)


⇒ 8 - 41 = - 3n + 3


⇒ - 33 = - 3n + 3


⇒ - 33 - 3 = - 3n


⇒ - 3n = - 36


⇒ n = 36/3


⇒ n = 12


∴ Number of terms = 12.


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