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The value of 01xexdx\int_0^1 x e^x dx is:

Solution

Correct Option: 3

When integrating a product of different types of functions like xx and exe^x, use integration by parts.

udv=uvvdu\int u \, dv = uv - \int v \, du

Using the ILATE rule (Inverse, Logarithmic, Algebraic, Trigonometric, Exponential), choose the function that appears first as uu.

Let u=xu = x (Algebraic) and dv=exdxdv = e^x dx (Exponential)

Then du=dxdu = dx and v=exv = e^x


Applying integration by parts:

xexdx=xexexdx\int x e^x dx = x \cdot e^x - \int e^x \cdot dx

=xexex+C= x e^x - e^x + C

=ex(x1)+C= e^x(x - 1) + C


Evaluating the definite integral from 0 to 1:

01xexdx=[ex(x1)]01\int_0^1 x e^x dx = \left[e^x(x - 1)\right]_0^1

At x=1x = 1:

e1(11)=0e^1(1 - 1) = 0

At x=0x = 0:

e0(01)=1e^0(0 - 1) = -1


01xexdx=0(1)\int_0^1 x e^x dx = 0 - (-1)

=1= 1

Therefore, the value is 11.

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