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NCERT Class XII Mathematics Chapter - - Solutions

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Prove the following (Exercises 262 to 267)
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Question : 263 of 271
Marks: +1, -0
∫01xexdx=1\int\limits_{0}^{1} x e^x dx = 1
Solution:  
Let I=∫01xexdxI = \int\limits_{0}^{1} x e^x dx
Integrating by parts, we get
[x∫exdx−∫(ddxx∫exdx)dx]01\left[ x \int e^x dx - \int \left( \frac{d}{dx} x \int e^x dx \right) dx \right]_{0}^{1}
=[x∫ex−∫exdx]01= \left[ x \int e^x - \int e^x dx \right]_{0}^{1}
=[xex−ex]01= \left[ x e^x - e^x \right]_{0}^{1}
=[(e−0)−(e−1)]=1= \left[ (e-0) - (e-1) \right] = 1
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