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Need solution for RD Sharma Maths Class 12 Chapter 20 Areas of Bounded Regions exercise 20.3 question 22.

Answers (1)

Answer:

\frac{32}{3} sq. Units

Hint:

Use concept.

Given:

The given  equations are y=2x^2  and y=x^2+4  

Solution:

To find the area enclosed by,

y=2x^2        ........(i)

y=x^2+4        ........(ii)

On solving the equation (i) and (ii),

2x^2=x^2+4

or x^2=4

or x=\pm 2

\therefore y=8

 Equation (1) represents a parabola with vertex (0, 0) and axis as y - axis.

 Equation (2) represents a parabola with vertex (0,4) and axis as the y - axis.

 Points of intersection of parabolas are A(2, 8) and B(– 2, 8).

These are shown in the graph below:

Required area=Region AOBCA

                          =2(RegionAOCA)

\begin{aligned} &=2 \int_{0}^{2}\left(x^{2}+4-2 x^{2}\right) d x \\ &=2 \int_{0}^{2}\left(4-x^{2}\right) d x \\ &=2\left[4 x-\frac{x^{3}}{3}\right]_{0}^{2} \\ &=2\left[\left(8-\frac{8}{3}\right)-0\right] \\ &=\frac{32}{3} \text { sq.units } \end{aligned}

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