Question

if the value of "y" varies directly with "x" and y = -8 when x = 4 find "y" when x = -4 enter the number that belongs in the green box. y = ?

Answer 1

We have the following:

Since they vary directly, it means that they are directly proportional, therefore

`\begin{gathered} x=4\rightarrow y=-8 \\ x=-4\rightarrow y=? \end{gathered}`

solving:

`\begin{gathered} y=mx \\ \text{replacing} \\ -8=m\cdot4 \\ m=(-8)/(4) \\ m=-2 \end{gathered}`

now, replacing

`y=-2\cdot-4=8`

Therefore, the answe is 8