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Question: Answered & Verified by Expert
If y=enx, then d2ydx2.d2xdy2  is equal to :
MathematicsDifferentiationJEE MainJEE Main 2014 (09 Apr Online)
Options:
  • A ne-nx
  • B -ne-nx
  • C nenx
  • D 1
Solution:
1990 Upvotes Verified Answer
The correct answer is: -ne-nx
y=enx ⇒ dydx=nenx ddxeax=aeax

    ⇒ d2ydx2=n2enx

dydx=nenxdxdy=1nenx=1ne-nx

           d2xdy2=ddydxdy

             =ddxdxdy·dxdy

               =ddx1ne-nx·e-nxn

               =1n-ne-nx·e-nxn

               =-1ne-2nx

⇒   d2ydx2.d2xdy2=n2enx×-e-2nxn

                       =-ne-nx

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