JEE 2023 — Mathematics PYQ
JEE | Mathematics | 2023For three positive integers p,q,r, xpq2=yqr=zp2r and r=pq+1 such that 3,3logyx,3logzy,7logxz are in A.P. with common difference 21. Then r−p−q is equal to:
Choose the correct answer:
- A.
-6
- B.
12
- C.
6
- D.
2
(Correct Answer)
2
Explanation
Solution
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A.P. Series: Di gayi series hai 3,3.5,4,4.5.
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3logyx=3.5⟹logyx=67
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3logzy=4⟹logzy=34
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7logxz=4.5⟹logxz=149
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Powers Relation: Maan lijiye xpq2=yqr=zp2r=K.
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x=K1/pq2,y=K1/qr,z=K1/p2r.
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Substitution: logyx=1/qr1/pq2=pqr=67.
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Kyonki r=pq+1, isliye pqpq+1=67⟹6pq+6=7pq⟹pq=6 aur r=7.
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p aur q nikalna: Doosre relation logzy=1/p2r1/qr=qp2=34 ka use karke:
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3p2=4q. pq=6 se q=6/p rakhne par: 3p2=4(6/p)⟹3p3=24⟹p3=8⟹p=2.
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Agar p=2, to q=6/2=3.
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Final Value: r−p−q=7−2−3=2. (Option D)
Explanation
Solution
-
A.P. Series: Di gayi series hai 3,3.5,4,4.5.
-
3logyx=3.5⟹logyx=67
-
3logzy=4⟹logzy=34
-
7logxz=4.5⟹logxz=149
-
-
Powers Relation: Maan lijiye xpq2=yqr=zp2r=K.
-
x=K1/pq2,y=K1/qr,z=K1/p2r.
-
-
Substitution: logyx=1/qr1/pq2=pqr=67.
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Kyonki r=pq+1, isliye pqpq+1=67⟹6pq+6=7pq⟹pq=6 aur r=7.
-
-
p aur q nikalna: Doosre relation logzy=1/p2r1/qr=qp2=34 ka use karke:
-
3p2=4q. pq=6 se q=6/p rakhne par: 3p2=4(6/p)⟹3p3=24⟹p3=8⟹p=2.
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Agar p=2, to q=6/2=3.
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Final Value: r−p−q=7−2−3=2. (Option D)

