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The area (in sq. units) of the region bounded by the parabola y2=4xy^2 = 4x and the line x=1x = 1 is

Solution

✅ Correct Option: 4

The region is bounded by the parabola y2=4xy^2 = 4x and the vertical line x=1x = 1.

The parabola y2=4xy^2 = 4x opens to the right.

To find intersection points, substitute x=1x = 1 into the parabola equation:

y2=4(1)y^2 = 4(1)

y2=4y^2 = 4

y=±2y = \pm 2

The curves intersect at (1,2)(1, 2) and (1,−2)(1, -2).


From the parabola equation y2=4xy^2 = 4x, we can write:

x=y24x = \frac{y^2}{4}

For any value of yy between −2-2 and 22:

Right boundary: x=1x = 1

Left boundary: x=y24x = \frac{y^2}{4}

The horizontal width of a strip is 1−y241 - \frac{y^2}{4}.


The area is:

A=∫−22(1−y24)dyA = \int_{-2}^{2} \left(1 - \frac{y^2}{4}\right) dy

A=[y−y312]−22A = \left[y - \frac{y^3}{12}\right]_{-2}^{2}


At y=2y = 2:

2−(2)3122 - \frac{(2)^3}{12}

=2−812= 2 - \frac{8}{12}

=2−23= 2 - \frac{2}{3}

=43= \frac{4}{3}

At y=−2y = -2:

−2−(−2)312-2 - \frac{(-2)^3}{12}

=−2−−812= -2 - \frac{-8}{12}

=−2+23= -2 + \frac{2}{3}

=−43= -\frac{4}{3}


A=43−(−43)A = \frac{4}{3} - \left(-\frac{4}{3}\right)

A=43+43A = \frac{4}{3} + \frac{4}{3}

A=83A = \frac{8}{3}

Therefore, the area of the region is 83\frac{8}{3} square units.

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