Question

If y varies jointly as x and z, and y = 20, x = 2, and z = 5, then find k, the constant of variation.
a. 10
b. 4
c. 2
d. 2/5
e. 5/2

Answer 1

varies jointly, meaning
"y" varies DIRECTLY in relation to "x" and "z".... thus \(\bf \begin{array}{cccllll}
\textit{something }&\textit{varies directly to }&\textit{something else}\\ \quad \\
\textit{something }&={\color{red}{ \textit{some value }}}&\textit{something else}\\ \quad \\
y&={\color{red}{ n}}&xz&\implies y={\color{red}{ n}}xz
\end{array}\\ \quad \\
y=20\qquad x=2\qquad z=5\implies y={\color{red}{ n}}xz\to 20={\color{red}{ n}}\cdot 2\cdot 5\)

so you'd just need to find "n", or the "constant of variation"

Answer 2

thank you so much!!!