In exercise 5.3 of arithmetic progressions of math of class 10th. How i solve this tough question in easy way In an AP(vii) Given a = 8, an = 62, Sn = 210, find n and d.
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Given that, a = 8, an = 62, Sn = 210
As, sum of n terms in an AP is,
Sn = n/2 (a + an)
210 = n/2 (8 +62)
⇒ 35n = 210
⇒ n = 210/35 = 6
Now, 62 = 8+5d
⇒ 5d = 62-8 = 54
⇒ d = 54/5 = 10.8