If 19th term of a non-zero AP is zero, then its (49th term)… — JEE Main 2019 Mathematics PYQ

JEE Main 2019 · 11 Jan · Shift II

If 19th term of a non-zero AP is zero, then its (49th term) : (29th term) is

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Correct option: D

Solution

a₁₉ = a + 18d = 0, so a = -18d.

49th term = a + 48d = -18d + 48d = 30d
29th term = a + 28d = -18d + 28d = 10d

Ratio = 30d : 10d = 3 : 1.

[JEE Main 2019 · 11 Jan · Shift II]

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