Question

Y varies directly as x. y =84 when x=6. Find y when x=12y= ?

Answer 1

If y varies directly as x, we have that

`y\propto x`

Then

`y=kx(where\text{ k is a constant\rparen}`
`\begin{gathered} When\text{ y=84 , x= 6} \\ y=kx \\ 84=6k \\ k=(84)/(6)=14 \end{gathered}`

The relationship between x and y is given as

`\begin{gathered} y=kx \\ y=14x \end{gathered}`

Therefore when x= 12, y=?

`\begin{gathered} y=14x \\ y=14*12=168 \end{gathered}`

Hence, the value of y when x = 12 is 168

Final answer: y = 168