Question

Write an appropriate inverse variation equation if y = 9 when x = 3.

Answer 1

$\bf \qquad \qquad \textit{direct proportional variation}\\\\ \textit{\underline{y} varies directly with \underline{x}}\qquad \qquad y=kx\impliedby \begin{array}{llll} k=constant\ of\\ \qquad variation \end{array}\\\\ -------------------------------\\\\ \begin{cases} y=9\\ x=3 \end{cases}\implies 9=k3\implies \cfrac{9}{3}=k\implies \boxed{3=k} \\\\\\ thus\qquad y=3x$