$\int_{-3}^0 x \sqrt{x+4} d x=$

$\int_{-3}^0 x \sqrt{x+4} d x=$
  1. $\frac{-94}{15}$
  2. $\frac{94}{15}$
  3. $\frac{-34}{15}$
  4. $\frac{64}{15}$

Solution

$\int_{-3}^0 x \sqrt{x+4} d x$ let $x+4=t$ $\begin{aligned} & \Rightarrow x=t-4 \\ & \Rightarrow \mathrm{d} x=\mathrm{d} t \end{aligned}$ when $x=-3, t=1$ when $x=0, t=4$ $\begin{aligned} & \int_1^4(t-4) \sqrt{t} \mathrm{~d} t=\int_1^4\left(t^{3 / 2}-4 t^{1 / 2}\right) \mathrm{d} t=\left[\frac{2}{5} t^{5 / 2}-\frac{8}{3} t^{3 / 2}\right]_1^4 \\ & =\frac{2}{5}(32-1)-\frac{8}{3}(8-1)=\frac{186-280}{15}=-\frac{94}{15}\end{aligned}$

Asked in: MHT CET 2022 (10 Aug Shift 1)

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