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Question: Answered & Verified by Expert
The integral 1exe2x-exxlogex  dx is equal to
MathematicsDefinite IntegrationJEE MainJEE Main 2019 (12 Jan Shift 2)
Options:
  • A 32-e-12e2
  • B 12-e-1e2
  • C -12+1e-12e2
  • D 32-1e-12e2
Solution:
2976 Upvotes Verified Answer
The correct answer is: 32-e-12e2

Let I1=1exe2xlogex dx

Let xex=t

Taking natural logarithm on both sides, we get

xln x e =ln t

xln x1=lnt  .........i

x t
1 1ln1-1=lntt=1e
e elne-1=lntt=1

Differentiating equation i on both the sides, we get

lnx1+x1xdx=1tdt

⇒lnxdx=1tdt

I1=1e1t21tdt=t221e1=12-12e2

and I2=1eexxlogexdx

Let exx=t

Taking natural logarithm on both sides, we get

xlnex=lnt

x1-lnx=lnt  .........ii

x t
1 11-ln1=lntt=e
e e1-lne=lntt=1

Differentiating equation ii both sides, we get

x0-1x+1-lnx.1dx=dtt (using product rule of differentiation)

lnx=-dtt

I2=e1t.-dtt=-te1=-1--e=e-1

Hence, required integral is I1-I2

=12-12e2-e-1

=32-e-12e2.

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