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NCERT Class XII Mathematics Chapter - - Solutions

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Exercise - 7.2
Integrate the functions in Exercises 23 to 59.
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Question : 39 of 271
Marks: +1, -0
xex2\frac{x}{e^{x^2}}
Solution:  
Let I=∫xex2 dxI=\int \frac{x}{e^{x^2}}\,dx
Put x2=tx^2 = t ⇒2x dx=dt\Rightarrow 2x\,dx = dt
∴I=12∫dtet=12∫e−t dt\therefore I=\frac{1}{2}\int\frac{dt}{e^t}=\frac{1}{2}\int e^{-t}\,dt =12(e−t−1)+C=\frac{1}{2}\left(\frac{e^{-t}}{-1}\right)+C =−12et+C=-\frac{1}{2e^t}+C =−12ex2+C=-\frac{1}{2e^{x^2}}+C
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