Final answer:
The equation v = πr²h represents direct variation in mathematics.
Step-by-step explanation:
The equation given, v = πr²h, represents a direct variation.
In direct variation, two quantities are directly proportional to each other. This means that as one quantity increases, the other quantity also increases, and as one quantity decreases, the other quantity also decreases.
In this case, the volume (v) of a cylinder is directly proportional to the product of the base area (πr²) and the height (h).
For example, if the radius (r) of the cylinder doubles, the volume (v) will also double, assuming the height (h) remains the same.