$\int x^{3} \cdot e^{x^{2}} d x=$

$\int x^{3} \cdot e^{x^{2}} d x=$
  1. $\frac{1}{2} e^{x^{2}}\left(x^{2}+1\right)+c$
  2. $\frac{1}{2} e^{x^{2}}\left(x^{2}-1\right)+c$
  3. $\frac{1}{2} e^{x}\left(x^{2}-1\right)+c$
  4. $\frac{1}{2} e^{x}\left(x^{2}+1\right)+c$

Solution

Let $I=\int x^{3} e^{x^{2}} d x$ Put $x^{2}=t \Rightarrow 2 x d x=d t \Rightarrow x d x=\frac{1}{2} d t$ $\therefore \mathrm{I}=\frac{1}{2} \int \mathrm{te}^{\mathrm{t}} \mathrm{dt}$ $=\frac{1}{2}\left[t e^{t}-e^{t}\right]+c=\frac{1}{2} e^{t}(t-1)+c=\frac{1}{2} e^{x^{2}}\left(x^{2}-1\right)+c$

Asked in: MHT CET 2020 (13 Oct Shift 2)

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