MHB Inverse variation or direct or neither?

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The volume of a sphere, represented by the formula V=(4/3)pi*r^3, demonstrates a direct variation with the cube of the radius, r^3. While some may initially perceive it as direct variation with r, it is important to clarify that V does not vary directly with r itself. Instead, the relationship is defined by the constant factor (4/3)pi, indicating that volume increases with the cube of the radius. Therefore, the correct interpretation is that the volume varies directly with r^3, not r. Understanding this distinction is crucial in mathematical discussions of variation.
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the volume of a sphere: V=(4/3)pi*r3

To me it looks like it is direct variation with a power function (V/r3=(4/3)*pi)but i don't think that's what they're looking for
 
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Strictly speaking, neither, as $V$ does not vary directly with $r$.

It does, however, vary directly with $r^3$, as $\dfrac{4}{3}\pi$ is a constant.
 

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