The area (in sq. units) of the region \(\{(x, y): y^{2} \le x \le 2y\}\) is
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \(\displaystyle\frac{4}{3}\)
For each y, x runs from the parabola \(x = y^{2}\) to the line x = 2y. This is possible only when
\(y^{2} \le 2y\)
\(y(y-2) \le 0\)
\(0 \le y \le 2\)
So the region is found by integrating in y, with width \(2y-y^{2}\):
\( \displaystyle A = \int_{0}^{2}(2y-y^{2})\,dy \)
\( \displaystyle = \left[y^{2}-\frac{y^{3}}{3}\right]_{0}^{2} \)
\( \displaystyle = 4-\frac{8}{3} = \frac{4}{3} \)