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The value of the definite integral ∫01ex(1−x)2(1+x2)2dx\int_0^1 e^x \frac{(1-x)^2}{(1+x^2)^2}dx is:

Solution

✅ Correct Option: 2

The definite integral to evaluate is ∫01ex(1−x)2(1+x2)2dx\int_0^1 e^x \frac{(1-x)^2}{(1+x^2)^2}dx.

Expand (1−x)2(1-x)^2:

(1−x)2=1−2x+x2(1-x)^2 = 1 - 2x + x^2

The integral becomes:

∫01ex1−2x+x2(1+x2)2dx\int_0^1 e^x \frac{1 - 2x + x^2}{(1+x^2)^2}dx


Regroup the numerator as (1+x2)−2x(1 + x^2) - 2x:

∫01ex1+x2−2x(1+x2)2dx\int_0^1 e^x \frac{1 + x^2 - 2x}{(1+x^2)^2}dx

Split into two integrals:

∫01ex1+x2(1+x2)2dx−∫01ex2x(1+x2)2dx\int_0^1 e^x \frac{1 + x^2}{(1+x^2)^2}dx - \int_0^1 e^x \frac{2x}{(1+x^2)^2}dx

=∫01ex1+x2dx−∫01ex2x(1+x2)2dx= \int_0^1 \frac{e^x}{1+x^2}dx - \int_0^1 e^x \frac{2x}{(1+x^2)^2}dx


Note that:

ddx[11+x2]=−2x(1+x2)2\frac{d}{dx}\left[\frac{1}{1+x^2}\right] = \frac{-2x}{(1+x^2)^2}

Therefore:

2x(1+x2)2=−ddx[11+x2]\frac{2x}{(1+x^2)^2} = -\frac{d}{dx}\left[\frac{1}{1+x^2}\right]


For the second integral, apply integration by parts:

∫01exddx[11+x2]dx=[ex⋅11+x2]01−∫01ex11+x2dx\int_0^1 e^x \frac{d}{dx}\left[\frac{1}{1+x^2}\right]dx = \left[e^x \cdot \frac{1}{1+x^2}\right]_0^1 - \int_0^1 e^x \frac{1}{1+x^2}dx


Substituting back:

∫01ex1+x2dx−([ex⋅11+x2]01−∫01ex1+x2dx)\int_0^1 \frac{e^x}{1+x^2}dx - \left(\left[e^x \cdot \frac{1}{1+x^2}\right]_0^1 - \int_0^1 \frac{e^x}{1+x^2}dx\right)

The two ∫ex1+x2dx\int \frac{e^x}{1+x^2}dx terms cancel:

=−[ex⋅11+x2]01= -\left[e^x \cdot \frac{1}{1+x^2}\right]_0^1

=[ex⋅11+x2]01= \left[e^x \cdot \frac{1}{1+x^2}\right]_0^1


Evaluate at the limits:

At x=1x = 1: e11+12\frac{e^1}{1+1^2}

=e2= \frac{e}{2}

At x=0x = 0: e01+02\frac{e^0}{1+0^2}

=11= \frac{1}{1}

=1= 1

Therefore:

e2−1\frac{e}{2} - 1

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