The area (in sq units) bounded by the curves $x=-2 y^2$ and $x=1-3 y^2$ is

The area (in sq units) bounded by the curves $x=-2 y^2$ and $x=1-3 y^2$ is
  1. $\frac{2}{3}$
  2. $1$
  3. $\frac{2}{3}$
  4. $\frac{2}{3}$

Solution

Given curves, $ \text { and } \quad \begin{aligned} & x=-2 y^2 \\ & x=1-3 y^2 \end{aligned} $ On solving both curves, we get $ \begin{gathered} -2 y^2=1-3 y^2 \\ \Rightarrow \quad y= \pm 1 \text { and } x=-2 \end{gathered} $ So, the intersection points are $(-2,1)$ and $(-2,-1)$.
$\therefore$ Required area $ \begin{aligned} & =2 \int_0^1\left\{\left(1-3 y^2\right)-\left(-2 y^2\right)\right\} d y \\ & =2 \int_0^1\left(1-y^2\right) d y \\ & =2\left(y-\frac{y^3}{3}\right)_0^1=2\left(1-\frac{1}{3}\right) \\ & =2 \times \frac{2}{3}=\frac{4}{3} \end{aligned} $

Asked in: AP EAMCET 2013

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