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The area (in Sq. units) of the region bounded by y=−2y = -2, y=2y = 2, x=y3x = y^3 and x=0x = 0 is equal to

Solution

✅ Correct Option: 3

We need to find the area of a region with these boundaries:

y=2y = 2 (horizontal line at top)

y=−2y = -2 (horizontal line at bottom)

x=y3x = y^3 (a curve)

x=0x = 0 (the y-axis)

Since xx is expressed in terms of yy, we integrate with respect to yy.


Let's see what happens with the curve x=y3x = y^3:

When y=0y = 0, we get x=0x = 0

When y=2y = 2, we get x=8x = 8

When y=−2y = -2, we get x=−8x = -8

For negative yy values, xx becomes negative. The curve goes into the left side (negative xx region).


We split the region into two parts:

From y=−2y = -2 to y=0y = 0: The region lies between x=y3x = y^3 (left) and x=0x = 0 (right)

Width at any point =0−y3=−y3= 0 - y^3 = -y^3

From y=0y = 0 to y=2y = 2: The region lies between x=0x = 0 (left) and x=y3x = y^3 (right)

Width at any point =y3−0=y3= y^3 - 0 = y^3


Setting up the integration:

Total Area=∫−20(0−y3) dy+∫02(y3−0) dy\text{Total Area} = \int_{-2}^{0} (0 - y^3) \, dy + \int_{0}^{2} (y^3 - 0) \, dy

=∫−20(−y3) dy+∫02y3 dy= \int_{-2}^{0} (-y^3) \, dy + \int_{0}^{2} y^3 \, dy


Calculating the first integral:

∫−20(−y3) dy=[−y44]−20\int_{-2}^{0} (-y^3) \, dy = \left[-\frac{y^4}{4}\right]_{-2}^{0}

=−044−(−(−2)44)= -\frac{0^4}{4} - \left(-\frac{(-2)^4}{4}\right)

=0−(−164)= 0 - \left(-\frac{16}{4}\right)

=0+4=4= 0 + 4 = 4


Calculating the second integral:

∫02y3 dy=[y44]02\int_{0}^{2} y^3 \, dy = \left[\frac{y^4}{4}\right]_{0}^{2}

=244−044= \frac{2^4}{4} - \frac{0^4}{4}

=164−0=4= \frac{16}{4} - 0 = 4


Total Area=4+4=8 square units\text{Total Area} = 4 + 4 = 8 \text{ square units}

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