Q:

Suppose y varies directly with x. If y = -4 when x = 8, what is the equation of direct variation?Complete the steps to write the equation of direct variation.1. Start with the equation of direct variation y = kx.2. Substitute in the given values for x and y to get3. Solve fork to get4. Write the direct variation equation with the value found for k. The equation is​

Accepted Solution

A:
[tex]\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] \rule{34em}{0.25pt}\\\\ \textit{we also know that }~~ \begin{cases} y=-4\\ x=8 \end{cases}\implies -4=k(8)\implies \cfrac{-4}{8}=k\implies -\cfrac{1}{2}=k \\\\[-0.35em] ~\dotfill\\\\ ~\hfill y=-\cfrac{1}{2}x~\hfill[/tex]