The area of the region bounded by the curve $y=4 x-x^{2}$ and the $x$ -axis is

The area of the region bounded by the curve $y=4 x-x^{2}$ and the $x$ -axis is
  1. $\frac{16}{3}$ sq. units
  2. $\frac{32}{3}$ sq. units
  3. 32 sq. units
  4. 16 sq. units

Solution

We have $y=4 x-x^{2}$ When $y=0$, we get $x(4-x)=0 \Rightarrow x=0,4$ Required area is shaded. $\begin{aligned} \therefore A &=\int_{0}^{4}\left(4 x-x^{2}\right) d x \\ &=\left[\frac{4 x^{2}}{2}-\frac{x^{3}}{3}\right]_{0}^{4}=\left[2 x^{2}-\frac{x^{3}}{3}\right]_{0}^{4} \\ &=\left|2(16-0)-\frac{64-0}{3}\right|=\left|32-\frac{64}{3}\right| \\ &=\frac{32}{3} \end{aligned}$

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

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