JEE Main 2019 — Sequences And Series Question with Solution
From: JEE Main 2019 (Online) 9th April Morning Slot
Question
Let the sum of the first n terms of a non-constant
A.P., a1, a2, a3, ..... be , where
A is a constant. If d is the common difference of
this A.P., then the ordered pair (d, a50) is equal to
Choose an option
Show full solutionCorrect option: C
Correct answer
C(A, 50+46A)
Step-by-step explanation
Sn =
We know, nth tem
Tn = Sn - Sn - 1
= -
= 50 +
= 50 + A(n - 4)
We also know, common difference
d = Tn - Tn - 1
= 50 + A(n - 4) - 50 - A(n - 5)
= A
And T50 = 50 + A(50 - 4)
= 50 + 46A
(d, a50) = (A, 50+46A)
We know, nth tem
Tn = Sn - Sn - 1
= -
= 50 +
= 50 + A(n - 4)
We also know, common difference
d = Tn - Tn - 1
= 50 + A(n - 4) - 50 - A(n - 5)
= A
And T50 = 50 + A(50 - 4)
= 50 + 46A
(d, a50) = (A, 50+46A)
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This is a previous-year question from JEE Main 2019, covering the Sequences And Series chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.