Question

Help please! Suppose y varies directly with x, and y=14 when x= -4. What is the value of y when x= -6? a. -21 b. 10 c. 18 d. 21

Answer 1

\(\bf \begin{array}{cccllll}
\textit{something }&\textit{varies directly to }&\textit{something else}\\ \quad \\
\textit{something }&={\color{red}{ \textit{some value }}}&\textit{something else}\\ \quad \\
y&={\color{red}{ n}}&x&\implies y={\color{red}{ n}}x
\end{array}\\ \quad \\
y=14\qquad x=-4\qquad y={\color{red}{ n}}x\implies 14={\color{red}{ n}}(-4)\implies {\color{red}{ n}}=\square
\\ \quad \\
y={\color{red}{ \square }}x\quad \textit{what's "y" when x=-6?}\quad y={\color{red}{ \square }}(-6)\)

solve for "n" to find the "constant of variation", then plug it back in the equation
to find 'y" when x=-6, just set "x" to -6 and solve for "y"