Mathematics for IGCSE & O level - Proportion (Section 3 - No. 30)
What does the phrase "y varies directly as x^2" mean?
y = kx
y = k/x
y = kx^2
y = √x
Explication
The formula for direct proportionality is y = kx, and y varies directly with x^2 translates into y=kx^2.