Verified Solution • 2025–26 Session moderate

QJEEM19Maf127: JEE Main 2019 Mathematics - Class 11 JEEM19Maf127 Solution: Let x, y be positive real numbers and m, n positive integers.…

Let x, y be positive real numbers and m, n positive integers. The maximum value of the expression xmyn(1+x2m)(1+y2n){{{x^m}{y^n}} \over {\left( {1 + {x^{2m}}} \right)\left( {1 + {y^{2n}}} \right)}} is :

Multiple Choice Options

  • A 12{1 \over 2}
  • B 14{1 \over 4}
  • C m+n6mn{{m + n} \over {6mn}}
  • D 1

Step-by-Step Verified Solution

xmyn(1+x2m)(1+y2n)=1(xm+1xm)(yn+1yn)≤14{{{x^m}{y^n}} \over {\left( {1 + {x^{2m}}} \right)\left( {1 + {y^{2n}}} \right)}} = {1 \over {\left( {{x^m} + {1 \over {{x^m}}}} \right)\left( {{y^n} + {1 \over {{y^n}}}} \right)}} \le {1 \over 4}

using AM ≥\ge GM

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