Mathematics · Sequence and Series

JEE Main 2025 — 4 April, Evening Shift — Question 20

Consider two sets AA and BB, each containing three numbers in A.P. let the sum and the product of the elements of AA be 36 and pp respectively and the sum and the product of the elements of BB be 36 and qq respectively. Let dd and DD be the common differences of AP's in AA and BB respectively such that D=d+3D=d+3, d>0d>0. If p+qp−q=195\frac{p+q}{p-q}=\frac{19}{5}, then p−qp-q is equal to

  1. Option A:

    630630

  2. Option B:

    540540

    Correct
  3. Option C:

    450450

  4. Option D:

    600600

Answer: B

Step-by-step solution

Let the terms in AA be a1−d,a1,a1+da_{1}-d, a_{1}, a_{1}+d and in BB be a2−D,a2,a2+Da_{2}-D, a_{2}, a_{2}+D

Now 3a1=363 a_{1}=36

⇒a1=12\Rightarrow a_{1}=12 and 3a2=363 a_{2}=36

⇒a2=12\Rightarrow a_{2}=12

Now (12−d)(12)(12+d)=p(12-d)(12)(12+d)=p and (12−D)(12)(12+D)=q(12-D)(12)(12+D)=q

Also p+qp−q=195\frac{p+q}{p-q}=\frac{19}{5}

⇒12q=7p\Rightarrow 12 q=7 p

⇒12(12−D)(12)(12+D)=7(12−d)(12)(12+d)\Rightarrow 12(12-D)(12)(12+D)=7(12-d)(12)(12+d)

⇒12(9−d)(12)(15−d)=7(12−d)(12)(12+d)\Rightarrow 12(9-d)(12)(15-d)=7(12-d)(12)(12+d)

⇒12(135−d2−6d)=7(144−d2)\Rightarrow 12\left(135-d^{2}-6 d\right)=7\left(144-d^{2}\right)

⇒d=6,D=9\Rightarrow d=6, D=9

p=6×12×18=1296p=6 \times 12 \times 18=1296

q=756q=756

p−q=540p-q=540

Answer key and solution verified before publishing.

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Exam
JEE Main 2025
Subject
Mathematics
Chapter
Sequence and Series
Topic
Arithmetic Progression
Consider two sets A and B , each containing three numbers in A.P. let… | JEE Main 2025 PYQ with Solution · DhiX AI