If ∫ 0 1 1 5 + 2 x - 2 x 2 1 + e 2 - 4 x d x = 1 α log e α + 1 β ,   α ,…

If 0115+2x-2x21+e2-4xdx=1αlogeα+1β, α, β>0, then α4-β4 is equal to 
  1. 19
  2. -21
  3. 0
  4. 21

Solution

Given,

0115+2x-2x21+e2-4xdx=1αlogeα+1β

Now let,

I=1201152-x2-x1+e-4x-12dx

I=12011114-x-1221+e-4x-12dx

Now let x-12=tdx=dt

So, integral becomes,

I=12-121211122-t21+e-4tdt

I=12-12011122-t21+e-4tdt+1201211122-t21+e-4tdtI2

Now solving I2=12-121211122-t21+e-4tdt

Let t=-z, we get dt=-dz

So, I2=-12120dz1122-z21+e4z

I2=12012dt1122-t21+e4t

Now putting the value of I2 in I we get,

I=1201211122-t21+e-4t+11122-t21+e4tdt

I=12012e4t1122-t2e4t+1+11122-t21+e4tdt

I=1201211122-t2dt

I=12×12112ln112+t112-t012

I=1211ln11+111-1=1211ln(11+1)210

I=111ln11+110

Now on comparing with 1αlogeα+1β we get,

α=11, β=10α4-β4=21

Asked in: JEE Main 2023 (15 Apr Shift 1)

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