The area of the region bounded by the parabola $x^{2}=16 y, y=1, y=4$ and the Y-axis lying in the first…

The area of the region bounded by the parabola $x^{2}=16 y, y=1, y=4$ and the Y-axis lying in the first quartrant is
  1. $\frac{55}{3}$ sq. units
  2. $\frac{56}{3}$ sq. units
  3. $\frac{52}{3}$ sq. units
  4. $\frac{53}{3}$ sq. units

Solution

The equation of curve is $x^{2}=16 y \Rightarrow x=4 \sqrt{y}$ Required area is shaded. $\begin{aligned} A &=\int_{1}^{4} 4 \sqrt{y} d y=4 \int_{1}^{4} y^{\frac{1}{2}} d y=4\left[\frac{y^{\frac{3}{2}}}{\left(\frac{3}{2}\right)}\right]_{1}^{4} \\ &=\frac{8}{3}(4 \sqrt{4}-1)=\frac{8 \times 7}{3}=\frac{56}{3} \end{aligned}$

Asked in: MHT CET 2020 (19 Oct Shift 1)

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