The volume of the solid is 32 cubic units.
Given the following parameters
The length of each cross-section is determined by the horizontal distance (parallel to the x-axis) from one end of the parabola to the other.
Since [tex]y = 4 - x^2[/tex], make "x" the subject of the formula to have:
[tex]x^2 = 4-y\\x = \sqrt{4-y}[/tex]
The horizontal distance will be expressed as:
[tex]\sqrt{4-y} - (-\sqrt{4-y} ) = 2\sqrt{4-y}[/tex]
Next, is to determine the area of each cross-section.
This is the square of the section's side length and it is expressed as:
[tex]f(y)=(2\sqrt{4-y} )^2\\f(y) = 4(4-y)\\f(y) = 16 - 4y[/tex]
The volume of the solid will be expressed as:
[tex]v=\int\limits^4_0 {(16-4y)} dy\\ v = 16y - 2y^2 \\v =[16(4)-2(4)^2] - 0\\v=64-32\\v=32 units^3[/tex]
Hence the volume of the solid is 32 cubic units.
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