Question

z varies directly as x2 and inversely as y2. If z=76 when x=5 and y=2, find z if x=9 and y=9. (Round off your answer to the nearest hundredth.)

Answer 1

`\qquad \qquad \textit{combined proportional variation} \\\\ \begin{array}{llll} \textit{\underline{y} varies directly with \underline{x}}\\ \textit{and inversely with }\underline{z^5} \end{array} ~\hspace{6em} \stackrel{\textit{constant of variation}}{y=\cfrac{\stackrel{\downarrow }{k}x}{z^5}~\hfill } \\\\[-0.35em] ~\dotfill`

`\stackrel{ \begin{array}{llll} \textit{\small`