Question

Determine whether y varies directly with . If so, find the constant of variation and write the equation.

Answer 1

Yes,
`k=-(1)/(3)` and
`y=-(1)/(3)x`

Explanation:

Using (-6,2) and (-9,3)

We have
`k=(2-3)/(-6--9)=-(1)/(3)`

This implies that;

`y=-(1)/(3)x`

Checking for the third point,

When x=-15,

`y=-(1)/(3)(-15)=5`

Hence y varies directly as x.