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QJEEM22Ma3142: JEE Main 2022 Mathematics - Class 12 JEEM22Ma3142 Solution: Let be the solution curve of the differential equation , ,…

Let y=y(x)y=y(x) be the solution curve of the differential equation

sin⁡(2x2)log⁡e(tan⁡x2)dy+(4xy−42xsin⁡(x2−π4))dx=0\sin \left( {2{x^2}} \right){\log _e}\left( {\tan {x^2}} \right)dy + \left( {4xy - 4\sqrt 2 x\sin \left( {{x^2} - {\pi \over 4}} \right)} \right)dx = 0 , 0 < x < \sqrt {{\pi \over 2}} , which passes through the point (π6,1)\left(\sqrt{\frac{\pi}{6}}, 1\right) . Then ∣y(π3)∣\left|y\left(\sqrt{\frac{\pi}{3}}\right)\right| is equal to ______________.

Step-by-Step Verified Solution

dydx+y(4xsin⁡(2x2)ln⁡(tan⁡x2))=42xsin⁡(x2−π4)sin⁡(2x2)ln⁡(tan⁡x2){{dy} \over {dx}} + y\left( {{{4x} \over {\sin (2{x^2})\ln (\tan {x^2})}}} \right) = {{4\sqrt 2 x\sin \left( {{x^2} - {\pi \over 4}} \right)} \over {\sin (2{x^2})\ln (\tan {x^2})}}

I.F=e∫4xsin⁡(2x2)ln⁡(tan⁡x2)dxI.F = {e^{\int {{{4x} \over {\sin (2{x^2})\ln (\tan {x^2})}}dx} }}

=eln⁡∣ln⁡(tan⁡x2)=ln⁡(tan⁡x2)= {e^{\ln |\ln (\tan {x^2})}} = \ln (\tan {x^2})

∴\therefore ∫d(y.ln⁡(tan⁡x2))=∫42xsin⁡(x2−π4)sin⁡(2x2)dx\int {d(y.\ln (\tan {x^2})) = \int {{{4\sqrt 2 x\sin \left( {{x^2} - {\pi \over 4}} \right)} \over {\sin (2{x^2})}}dx} }

⇒yln⁡(tan⁡x2)=ln⁡∣sec⁡x2+tan⁡x2cosec x2−cot⁡x2∣+C\Rightarrow y\ln (\tan {x^2}) = \ln \left| {{{\sec {x^2} + \tan {x^2}} \over {{\mathop{\rm cosec}\nolimits} \,{x^2} - \cot {x^2}}}} \right| + C

ln⁡(13)=ln⁡(332−3)+C\ln \left( {{1 \over {\sqrt 3 }}} \right) = \ln \left( {{{{3 \over {\sqrt 3 }}} \over {2 - \sqrt 3 }}} \right) + C

e=ln⁡(13)−ln⁡(32−3)e = \ln \left( {{1 \over {\sqrt 3 }}} \right) - \ln \left( {{{\sqrt 3 } \over {2 - \sqrt 3 }}} \right)

For y(π3)y\left( {\sqrt {{\pi \over 3}} } \right)

yln⁡(3)=ln⁡∣2+323+13∣+ln⁡(13)−ln⁡(323)y\ln \left( {\sqrt 3 } \right) = \ln \left| {{{2 + \sqrt 3 } \over {{2 \over {\sqrt 3 }} + {1 \over {\sqrt 3 }}}}} \right| + \ln \left( {{1 \over {\sqrt 3 }}} \right) - \ln \left( {{{\sqrt 3 } \over {2\sqrt 3 }}} \right)

=ln⁡(2+3)+ln⁡(13)+ln⁡(13)−ln⁡(32−3)= \ln \left( {2 + \sqrt 3 } \right) + \ln \left( {{1 \over {\sqrt 3 }}} \right) + \ln \left( {{1 \over {\sqrt 3 }}} \right) - \ln \left( {{{\sqrt 3 } \over {2 - \sqrt 3 }}} \right)

⇒yln⁡3=ln⁡(13)\Rightarrow y\ln \sqrt 3 = \ln \left( {{1 \over {\sqrt 3 }}} \right)

⇒y2ln⁡3=−12ln⁡3\Rightarrow {y \over 2}\ln 3 = - {1 \over 2}\ln 3

⇒y=1\Rightarrow y = 1

∴\therefore ∣y(π3)∣=1\left| {y\left( {\sqrt {{\pi \over 3}} } \right)} \right| = 1 .

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