Mathematics for IGCSE & O level - Proportion (Section 1 - No. 25)
If *z* varies jointly with *x* and the square of *y*, then which of the following equations is true?
z= kx/y^2
z = ky^2/x
z = kxy^2
z = k/xy^2
Spiegazione
Joint variation means z is proportional to the product of x and y^2, or z = kxy^2