## Algebra and Trigonometry 10th Edition

$y$ varies directly as the square of $x$.
It means that if we multiply $x$ by a factor $a$, then $y$ will be multiplied by a factor $a^2$ $y_1=2x_1^2$ Now suppose that $x_2=ax_1$ $y_2=2x_2^2=2(ax_1)^2=2a^2x_1^2=a^2(2x_1^2)=a^2y_1$ $y_2=a^2y_1$