Question

Suppose y varies directly as x, and y = 8 when x = -2. Which of the following is the correct equation to set up to solve for the constant of variation?
A) 8 = k(-2)

B) -2 = k(8)

C) -2/8 = k/1

D) k = (-2) - 8

Answer 1

$\bf \qquad \qquad \textit{direct proportional variation} \\\\ \textit{\underline{y} varies directly with \underline{x}}\qquad \qquad y=kx\impliedby \begin{array}{llll} k=constant\ of\\ \qquad variation \end{array} \\\\[-0.35em] ~\dotfill\\\\ \begin{cases} y=8\\ x=-2 \end{cases}\implies 8=k(-2)$