Progression (Sequence and Series)Hard
Question
Let a1, a2, a3,..... be in harmonic progression with a1 = 5 and a20 = 25. The least positive integer n forwhich an < 0
Options
A.22
B.23
C.24
D.25
Solution
a1, a2, a3, are in H.P.
.......are in A.P.
+ (n - 1) d > 0, where 
n - 1 >
+ 1 ⇒ n ≥ 25.
.......are in A.P. + (n - 1) d > 0, where n - 1 >
+ 1 ⇒ n ≥ 25.Create a free account to view solution
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