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Direct Variation with the Square of a Variable

When a variable yy varies directly with the square of another variable xx, the relationship is expressed as:

y=kx2,where k0y = kx^2, \quad \text{where } k \neq 0

This extends the basic direct variation formula y=kxy = kx by replacing the first power of xx with x2x^2. The constant kk is still called the constant of variation and is found the same way: substitute a known pair of values into the equation and solve for kk. Once kk is determined, the equation can be used to find yy for any other value of xx. Because the variable is squared, the effect of changes in xx is amplified — for example, doubling xx will quadruple yy (since (2x)2=4x2(2x)^2 = 4x^2), rather than merely doubling it as in ordinary direct variation.

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Updated 2026-04-21

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