Question

Write an appropriate direct variation equation if y = 8 when x = 2

Answer 1

$\bf \qquad \qquad \textit{direct proportional variation}\\\\ \textit{\underline{y} varies directly with \underline{x}}\qquad \qquad y=kx\impliedby \begin{array}{llll} k=constant\ of\\ variation \end{array}\\\\ -------------------------------\\\\ \begin{cases} y=8\\ x=2 \end{cases}\implies 8=k2\implies \cfrac{8}{2}=k\implies 4=k \\\\\\ thus\qquad \qquad \boxed{y=4x}$